Great personalities do not come from genes

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This article by Dr Piotr Wozniak is part of SuperMemo Guru series on memory, learning, creativity, and problem solving.

Erroneous model of schooling

There is a growing awareness of the harms of discrimination. However, few people realize the harm of discrimination of the basis of personality. As much as it is easier to discriminate on the basis of labels, such as skin color, it is also easier to see the harm of discrimination, which is also well labelled.

Discrimination based on personality is universal and contributes to a great deal of the harm of compulsory schooling. The education system has built an efficient sieve for shaping and selecting for a specific set of personality traits. It uses the sieve to funnel successive generations through the ladders of the system towards an illusory elite status where the acme of intelligence allegedly resides. In the process, millions suffer a harm to their mental health and their intelligence. Paradoxically, the greatest harm is often found at the top of the ladder, and the selection process on the way may actually be a great safety valve against destroying the fabric of society.

At the bottom of that discriminatory selection process lays a conviction that people, their personality and their intelligence are somehow encoded in the genes and unchangeable. At each stage of the selection, the weaker product is being tossed out from the educational assembly line. The alternative education system that would allow individuals to thrive in their own ways is largely elusive, unrecognized and unfathomed. And yet, it is based on a stunningly simple ingredient: freedom (see: Lex Libertas).

In terms of shaping the personality, the education system asks for curiosity but generates indifference. It asks for conscientiousness but generates futile grit. It asks for extroversion but generates two-faced introverts. It asks for agreeableness but generates and inauthentic facade of niceness. Last but not least: the education system based on coercion generates a neurotic society prone to depression and addictions.

In other words, instead of maximizing human potential, the education system rejects entire swathes of society and destroys the personality of those who survive in the system. I feel like I survived both the selection and the compressive forces of the funnel. I spent 22 years in the system and could observe its impact at each stage. In the following 35 years of freedom, by virtue of my job, I had a chance to recover and discover what true education is. This is why I feel uniquely qualified and obliged to call for a change.

In this text, I want to explain why we need to depart from the genetic model of personality. The model marks some people as pathological element that is of little use to society. Others are called insufficiently intelligent, or lazy, or disruptive. We have a plethora of labels that provide alternative "inferior" education pathways for dyslexics, for ADHD, for Aspergers and a rapidly swelling population of the autistic spectrum that spreads from those who truly cannot perform basic life functions to those who have all the qualities of a young Einstein.

Genetic models of personality underlie the discriminatory harm of the coercive education system

Harm of the genetic perspective

The belief that personality traits are set in genetic stone is harmful. It obscures the negative impact of authoritarian parenting, coercive schooling, and other restrictions on freedom of development. Humans are usually born with fantastic personalities. Their main quality is adaptability. It is the loss of adaptability that provides the illusion of non-malleability. The deprivation of the freedom of development results in personality changes that solidify the myth of genetic determinism.

Life's adversities erode the adaptability of personality

Personality is plastic

Personality is affected by thousands of genes, but the effects of genes are not deterministic. I will argue here that personality is primarily shaped by the environment. To say that personality is hereditary is not much more accurate than to say that basketball talent is hereditary just because taller babies are more likely to be talented basketballers.

There is no limit set on personality by non-deleterious genes

Setting aside the influence of our gene-focused culture and the legacy of the Human Genome Project, we might say that the wisdom of John Watson from 1930 still holds true:

Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in and I'll guarantee to take any one at random and train him to become any type of specialist I might select – doctor, lawyer, artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors

Watson's words seem obvious to everyone who studies learning, conditioning, or behavior. It is pretty obvious to experienced parents. However, the mythology of the personality genes is omnipresent.

We marvel over the genetics. "You got eyes after your mom", or "the same smile as your dad". And yet, all those different eyes and mouths have the same function. In healthy individuals, all different mouths are equally capable of satisfying our nutritional needs.

The same universal functional commonality is true of personality and intelligence, except they are far more plastic. Unlike bones or ligaments personality depends on the learning brain! - the most adaptable biological device on the planet.

Genetic studies

Identical twin studies may say that heredity of personality traits takes half of the role in nature vs. nurture interplay. However, to say personality is hereditary is highly misleading. If we want to see a planet populated with happy people, we need to make sure they grow up in conditions conducive for developing a thriving personality.

Given ideal conditions for upbringing, nearly all individuals end up with fantastic personalities. The correlations between genes and personality traits stem from the fact that minor gene variants can have major impact on personality outcomes in certain environments. A well-known deleterious mutation that affects intelligence and adaptability is phenylketonuria. This genetic disorder can easily be prevented with simple dietary adjustment.

The most well-documented genetic variants with a significant influence on cognitive ability include APOE. APOE-ε4 increases the chances of Alzheimer's. But prevention is again possible by simple lifestyle changes.

The story is the same in the case of genes that determine personalities. For example, our modern lifestyle makes many people neurotic. Some genes may favor resilience that prevents neuroticism. However, a change to more conducive environments could help most of the population rank low on neuroticism. In particular, authoritarian parenting and coercive schooling have a powerful impact on personality. In conditions of love and freedom, genetic differences fade. Can we then say personality is hereditary? It would be more accurate to say that the resilience to negative environmental influences on personality has a strong genetic background. In nurturing environments, nearly everyone turns out curious, scrupulous, extravert and nice.

A minor genetic factor such as attractiveness should have little effect on personality. However, in conditions of coercive schooling it may play an outsized role. Being attractive at school helps being popular, and consequently extrovert, and optimistic. It is easier to keep one's self-esteem unharmed at school.

Heredity studies show that uniform, suppressive, and homogenizing shared environments, e.g. coercive school will blow up the significance of the genes! In the wild, diversity may be wider, and more dependent on the environmental factors.

Suppressive environments blow up the significance of heredity

Developmental trajectory

Personalities can be measured by a personality test. We often hear that personalities run in families or that a specific characteristic is taken after a parent, or even a grandparent.

However, there is a hidden danger in adopting the view in which heredity plays a significant role in determining the personality. Heredity implies that individuals carry genetic trait variants that are largely immutable. This lessens the motivation or hope for change. In reality, all personality traits are highly plastic, and good care in childhood brings fantastic outcomes in a vast majority of individuals.

For example, all kids are born curious. Curiosity is the key to intelligence. It is an indispensable factor in human survival in most environments. At the same time, it is very easy to kill curiosity at school, or in an autocratic family where curious behaviors are penalized (see: Learned helplessness vs. learn drive).

Two horrible side effects of attributing curiosity or intelligence to heredity are:

  • kids are classified and selected as those who are more or less capable of learning
  • gradual decrease in curiosity that occurs in schooling is seen as a natural biological process (brain maturation)

The optimistic message that should come with this text is that a vast majority of kids are conceived curious, sociable, nice, and well-composed. In our not-so-healthy society, the first obstacle course is the pregnancy. The brain is shaped by the conceptualization process that begins in week 3 of gestation. The process is controlled by environmental input, and interfered with by noxious factors such as trauma, stress, toxins, nutritional deficits, infections, etc.

Given a healthy conception, a healthy mom and a healthy pregnancy, nearly all kids are born happy, curious and smart. The process of shaping a personality is largely based on destroying what's best, and to a lesser degree, amplifying the characteristics that turn out most useful in life.

As all personality traits are polygenic, I doubt we will ever discover a single personality gene whose non-detrimental variants could be detected in human behavior by an expert or by AI. The genes that play a role in shaping the temperament are all occurring in variants that introduce tiny changes in phenotypic outcomes. All those variants have their pros and cons. Those that are clearly detrimental are successively eliminated from the population.

It is the response to adversity that may differ. An abusive household will destroy a kid with certain gene variants and make another kid resilient due to another variant. Without abuse, both kids would turn out great. If we removed noxious influences, heritability might drop dramatically.

There might exist an optimum gene set that could yield the best astronaut, or the best mathematician. However, as there are no significant evolutionary pressures to generate such an optimum set, we can safely assume that all healthy kids are born with a mosaic that will turn out optimum for a specific niche in the course of sampling and adaptation to specific environments.

The majority of healthy kids can become astronauts or great mathematicians as long as we do not undermine their potential in achieving that goal. Even if genes form an obstacle, the kids will naturally drift towards their strengths given freedom in conducive environments.

It is the environment that makes the most of the difference, and few non-deleterious alleles produce effects that can break through environmental influences. Those that make a difference, usually make a difference for the worse, and are likely to be on the decline in populations.

Brain is highly plastic, and the hand we get dealt at birth is secondary

Big Five is just a word game

A popular myth says that the Big Five has been delineated as a result of studying genetic traits. In reality, it is just a factor analysis of words used to describe personality. There are nearly 5000 such words in English. We can safely say that if a personality characteristic is important, it will find its reflection in the language (lexical hypothesis).

With the help of factor analysis, the words describing personality can be grouped into a smaller number of categories, e.g. 16 or 5 depending on the coarseness of the grouping.

In Big Five set, the words have been grouped by various researchers by similarity until five seemingly irreducible dimensions have emerged. Big Five distinguishes five prime personality variables: openness, conscientiousness, extroversion, agreeableness and neuroticism. With its easy mnemonic OCEAN, one can quickly make a systematic personality assessment on a street corner. Pity the letter N is the only one that corresponds with a characteristic that is generally not wanted: neuroticism.

A great deal of effort in determining Big Five was done by language researchers, not psychologists!

I consider the Big Five classification highly flawed. If I was to describe my own personality, I would instantly miss (pathological) optimism or (pathological) stubbornness and reactance. How about impulsivity and aggression? Is it the opposite of agreeableness? I am considered pretty aggressive in sports. I love combat sports. However, I am also instantly classified as agreeable in face-to-face interaction. What about self-esteem? People who know me better call me arrogant; that's a direct derivative of high self-esteem. Why am I still agreeable then? Because I employ heavy auto-censoring and self-deprecation. I know I can achieve more by not being hated (due to arrogance or aggression). What about amorousness? Last but not least, why is intelligence not considered part of personality? Intelligence is as trainable as the rest of traits, and it is as important when interacting with people. It determines cognitive patters and fits the definition of a personality trait. Others observed missing traits such as egoism, manipulativeness, or thrill-seeking. For more see: Missing traits at the end of this text.

Importantly, we cannot find a gene or even a well-define gene set for any of the Big Five characteristics. It does not help that the most often cited personality gene, COMT may affect all the traits, esp. curiosity (O) and neuroticism (N).

Still, Big Five is a very useful concept backed up by thousands of publications and books. However, in my own writing, I use a terminology that is closer to real phenomena occurring in the brain. For example, I speak of the learn drive rather than hazy "openness to experience". Instead of conscientiousness or grit, I speak of easy-to-measure self-discipline.

Science of personality calls for new classifications (e.g. compare 16PF), but I can stick to the present level of imprecision and still prove the main thesis of this text beyond any doubt: personality is highly plastic.

Default personality

Happy babies

Babies are born seemingly with no personality. First smile usually comes only in 2-3 months. But from the very first minute, little humas are curious of the world. This is their defining characteristic. It is hard to notice significant differences in curiosity in little children as they grow up. Healthy babies score high on "openness to experience".

Once the deleterious genetic variants are sorted out (perhaps below 1% cases), we may say that humans are born with the default personality that is curious, pedantic, extroverted, pensive, sociable and resilient. This means that the default human is nice, smart, stable, and fun. Default personality takes the best of all traits in right proportions with minor variations that helps adapt to specific niches of human activity.

Heritability in young children is less pronounced than in adults

Cranky babies

Genes can determine the adaptation trajectory, but they cannot determine personality. Certain gene variants might slightly increase the chance for a high score in neuroticism. A specific set of non-deleterious genes may significantly increase that probability. However, we often hear that a baby was born fearful or cranky. That magnifies the conviction in the significance of genes. However, we have no way of knowing if this effect is not a result of the course of pregnancy.

Babies do not get depressed. We do not diagnose depression in the first years of life. The estimate of diagnosed depression for 3-year-olds is around 1%, and then it gradually increases with each year at school.

Cranky babies or high-needs babies are supposed to be a proof of hereditary temperament. However, cranky babies have alternative explanations.

A minor mutation might cause problems with digestion, which provides the first feedback loop between the moods of (1) herself and (2) her parents. The risk of neuroticism increases. Could we call that mutation a personality gene? And this is just one of a hundred possible examples due to the polygenic nature of personality.

If a parent comes with a crazy idea of planning baby sleep or the feeding schedule, she is on a sure way to make major unhappy cracks in the personality. Few people understand baby circadian cycle or lack thereof in the first months (see: Baby sleep). Schedules and planning are a sure prescription for a cranky baby.

What if a parent listens to American pediatrists with their crazy idea of shoving little babies to their own cots instead of feeling safe near mom's titty. This separation from the mom might be the main cause of crankiness and a clean start into the trait of neuroticism (see: Co-sleeping).

If you swear your baby was born cranky, many things might have happened in pregnancy.

A parental myth says that it is normal that a baby cries from time to time, or even a lot, or even 3 hours per day "on average". The only healthy reason for crying is an actual problem: primarily delayed or insufficient food, or lack of closeness with mom, or various health issues. An opposite assumption is safer: if a baby is crying, she has a serious reason to do so! Naturally, we can condition babies to cry too. A simple cruel way to prove it is to keep delaying food, and to deliver it instantly when the baby starts crying. This may result in crying as a conditional reflex. Crying is then simply a call for food. The same conditioning may result in crying as soon as baby suspects she might be abandoned in a cot or in a chair.

The temperament of a cranky baby has multiple alternative environmental explanations. Once born cranky, a baby may make her mom crankier, and the entire family may live in a cranky feedback loop. Once made cranky, it is hard to take the kid back to the default happy state. It is quite likely that she will keep going on a path towards marked neuroticism.

As mom is likely to share a great deal of genes with the baby, her own adaptation trajectory may be sensitive to those starting conditions. We may then have an illusion that crankiness runs in families. However, the same baby growing in a more conducive and tolerant environment may turn out a beacon of joy. Neuroticism is not determined by the genotype. Can we then call it hereditary?

It is those early adversities that make most of research seem to indicate that personalities are set in stone. However, the actual explanation is that (1) babies are most vulnerable to personality injury and (2) those early injuries are harder to reverse than those that occur later in childhood.

With a healthy pregnancy and natural parenting, chances for a cranky baby should drop dramatically

Happy centenarians

Research shows that most people become more agreeable, conscientious, extrovert, and less neurotic as they age. In retirement, with a newly acquired freedom, childhood curiosity can reawaken. Reverting back to the happy child-like personality might actually be one of the critical aspects of longevity. Happy and sunny predisposition reduces the risk of cancer, diabetes, and a whole array of other ailments.

Centenarians frequently revert to a happy baby personality

Cranky centenarians

This section is empty. I keep it just for symmetry. There are very few cranky centenarians. Crankiness does not serve longevity. Centenarians might be grumpy, but their life satisfaction is usually fantastic. This suggests strongly that contentment is a key ingredient of longevity!

Plasticity of personality

With a regular inflow of data showing how genes affect personality, it is easy to have doubts about the prime message of this text, which is to pay little attention to genetics in education. It is hard to demonstrate how little actual effect individual variations have, and hard to demonstrate the resultant effects of the complex symphony of synergistic and antagonistic influences on a polygenic scene.

My original dive into the myth of the power of the genes comes from understanding the plasticity of personality. The most convincing is the demonstration of how plastic brain adapts to the environment, and how individual traits can be modified to suit individual needs. In addition to the power of adaptation, we also need to be aware of the power of destructive influences that stem primarily from overriding natural adaptation with human-designed personality training, drill, taming, and breaking.

The first trait of Big Five's OCEAN is O = "openness to experience". This is a wide umbrella of characteristics with the common denominator: the learn drive.

The learn drive should actually be seen as the key component of plasticity for all personality traits. The learn drive is the basis of adaptation. It can strengthen conscientiousness of a medical student or a pragmatic neglect of secondary detail in a young mother. It can power the extroversion of a politician as much as the introversion of a mathematician. It makes people agreeable in the socialization process, but it also helps develop the necessary unkind toolset to handle unkind people. Finally, it helps develop stoic personality and resilience or enter the realm of learned neuroticism or induced neuroticism.

The learn drive is the key to understanding plasticity of personality

Conceptualization curve

The first major hint at the plasticity of personality is the fact that all traits tend to follow a conceptualization curve that is characteristic of all learning processes. The differences between kids tends to increase over time (source):

Individual differences in most traits tend to increase with age from early childhood into early adolescence and then plateau

In the picture below, the trait is marked as the capacity reflecting the volume of adaptation memory. The occurrence of plateau is a reflection of adaptive pressures. The model graph is typical of lifelong learning with a constant inflow of knowledge (optimally managed with spaced repetition). However, adaptive pressures reflect fluctuating interests and passions. In case of personality traits, we may safely say that for a set environment, the constellation of traits stabilizes within a few years. Hence the illusion that the personality of a 30-year-old remains stable. This in turn causes the illusion that personality traits might be written into the genotype.

Figure: Hypothetical course of learning and conceptualization in a fixed-size concept network. The naïve network begins the learning process at high plasticity (in red). As individual concepts form, they are consolidated and stabilized. The overall stability of the network keeps increasing (dark blue). The speed of conceptualization (in orange) is a resultant of plasticity and stability. It reaches its theoretical maximum somewhere on the way from the random graph stage to a sparse representation stage. This is the time of a large supply of concepts that may be subject to generalization, and a good balance between stabilization and forgetting. The overall problem solving capacity of the network (light blue) is negligible at first, and tends to saturate with network stabilization. Large number of well-stabilized concepts makes it harder to find new plastic network nodes for further conceptualization. The maximum capacity of the network depends on its size. Speed of learning in spaced repetition at older ages seems to indicate that the size of the concept network of the human brain is high enough to provide for lifelong learning without noticeable saturation. See: Conceptualization theory of childhood amnesia and How much knowledge can human brain hold

O: Openness to experience

Openness to experience is easiest to understand as curiosity. The popular and pop-psychological interpretation of openness to experience includes several vital components of human cognition that requires separate definition for the purpose of modelling mental computation. These separate traits are:

All those "sub-traits" are primarily shaped by the interaction with the environment. They can be summarized as intelligence and the potential to enhance intelligence. These "sub-traits" may be modulated and polygenic. Genes may modify the parameters of the concept network, which may, in the long run, find a reflection in the brain architecture. However, these characteristics in adults are primarily the expression of the developmental trajectory.

The learn drive explains the monumental role of curiosity for human well-being:

  • it defines the adaptability to the environment
  • it defines the plasticity of other personality traits
  • it determines human intelligence
  • it is the best warranty of health and longevity
  • it is the foundation of the joy of living

In healthy people, the learn drive is the most plastic of the Big Five characteristics. Once suppressed, the learn drive is the opposite: the least plastic and the hardest to fix aspect of personality.

A powerful learn drive is its own best amplifier. All healthy kids are well equipped from birth, but their drive to learn can be easily suppressed. The main suppressors are maternal separation, inept daycare, authoritarian parenting, and coercive schooling. Later in life, with the arrival of freedom, the learn drive tends to return. However, once suppressed, it can easily be kept in check by adversities of modern life such as corporate culture, social media, dysfunctional family, and more.

The learn drive is the most important personality characteristics that determines human well-being

C: Conscientiousness

Grit

Angela Duckworth popularized the word "grit", esp. in reference to conscientious study at school (see: Angela Duckworth is wrong about grit). Angela is blind to the harms of schooling, which she revealed in her answer to the audience here: Talks at Google (after 33 min). The key to healthy self-discipline (or grit) is passion. Schools destroy passions and rely on unhealthy grit instead. When a graduate asked what to be gritty about, he hinted that school makes it easy to be gritty, while real life leaves you with a post-school passionless void ("How to be gritty if the cost of wrong choices is so high"). Angela separated (1) interests (understood as childhood passions) and (2) purpose (understood as moral guidelines). This shows she does not realize that the only healthy passion is the one in where the two are networked and blended seamlessly. No wonder. She admits climbing the ladder of opportunity, searching for the next area to employ grit (esp. in education). A true passion begins early in life and keeps growing by accruing experiences and valuations (see: Knowledge valuation network). It is possible to build passions later in life, but they are rarely well integrated with the entirety of the knowledge network. Adaptation is a continual process. Changes of direction later in life will always leave a form of residue ballast unless the changes were sparked naturally in the course of life in response to events. Schools and colleges leave millions of graduates crippled for life due to robbing them of childhood passions (see: 100 bad habits learned at school). As a result, we live in unhappy societies driven by grit and self-discipline that quarrels with Self.

Angela is then right in diagnosing the problem:

Most of us do not even know what passion is until we find one

Duckworth's recommendation of grit is dangerous for mental health

When Scott Galloway advises people to ignore "follow your passion" advice, he is right only in that the advice is unworkable in most adults who have been washed out of passions and interests (primarily in the period of coercive schooling). See: Scott Galloway does not understand talent

"Follow your passions" is a great advice if given early enough

Adaptive conscientiousness

In the ideal case, conscientiousness is highly selective. Its intensity is a result of adaptation. It shows up most intense where it matters.

Personal anecdote. Why use anecdotes?
Conscientiousness has many faces in my own terminology: persistence, perfectionism, planning, etc. To the outside world I seem like the most conscientious human who ever lived. With my Plan, tasklists, incremental reading, diary, statistics, rigid habits, and rigid rules, I leave people with the impression of having no fun in life (see my: Simple formula for a happy life). In reality, I am conscientious only where it matters. I can be persistent with sports progression, perfectionistic with Plan or incremental reading, or totally elastic and spontaneous while interacting with people. In Plan, I use flexible Morning dilemma strategy. In SuperMemo, I use auto-postpone. My rules are rigid until they become unpragmatic and get replaced with new rules. At university, it was Krzysztof Biedalak who was truly conscientious. He made beautiful lecture notes. I would copy those notes sloppily when in need. I do not brush my teeth in the morning and use no shampoo. I clean my room probably once or twice per year. That's rational negligence. I do not have a rule for that. I may swim and run in the same shorts the entire summer. In the area of health and work, I am pretty conscientious. Elsewhere, I am a mess. What is the psychologist's verdict? One-sided questions of personality questionnaires make me highly conscientious. In reality, I am hardly
Conscientiousness is too plastic to be genetic

Perfectionism is plastic

My own life is a great illustration how perfectionism affects a given area of passionate pursuit. When priorities change, perfectionism can be replaced with being more relaxed and less caring. It can also be cancelled by giving up on a pursuit.

Personal anecdote. Why use anecdotes?
I am sometimes asked if I am autistic. In multiple personal notes at supermemo.guru, I left quite a deal of evidence showing unusual conscientiousness or perfectionism verging on OCD. At the age of 12, I started collecting sport newspapers that I organized on multiple shelves in bookcases at home. As I often retrieved those papers from wastepaper facilities, each had to be cleaned up, restored and meticulously pressed with an iron. That raises a red flag (some exclaim: "Aspergers!"). Observers noted that my meticulousness led to spaced repetition. Indeed, I showed little tolerance to forgetting. I wanted all my investments in learning to be preserved. Meticulous notes on the dates and outcomes of repetitions required a bit of conscientious record keeping.

However, I can be horribly inattentive too. I make efforts to organize or clean my room extremely rarely. Perhaps twice per year? All I care is to never bring meals to my room and never enter home without washing feet first. A covid test I took during one of our anniversary debates is still on my desk waiting to be pictured and disposed of!

I cured myself from my newspaper perfectionism by just getting tired of the required investment in time. At some point, I stopped collecting older papers. Then I reduced my reading about sports as my interests in chemistry and biochemistry kept increasing in parallel. Then the shelves with paper stopped growing. After a few years, the papers landed in wastepaper collecting point bringing some meager income. Paper collecting-and-pressing perfectionism died and was replaced by new obsessions.

My work with SuperMemo also evolved from being strict with the Outstanding material. I moved from various streaks reminiscent of Duolingo, to total freedom and chaos. I do not mind for the chaos to be organized excruciatingly slowly. I do not mind heavy postpones in my collections. It took me quite a while to move from conscientiousness, to the priority queue, to finally focusing on knowledge that brings highest returns for investments in time. Those investments I do not measure on any scale. I just follow the passion of exploration. Incremental reading makes learning fun, cheap and effective.

Today, I am most conscientious about Plan, incremental reading, tasklists and sports. In sports, I always like to work on some progression curve. It can be jogging, swimming or strength. This summer it was ultramarathon, butterfly, bench presses, and a dead lift. When I enter the progression, I progress religiously. When I hit the limit, I change the discipline. This usually comes in coincidence with a change in seasons. Clearly perfectionist obsessions may be born and may die. Whith a rational and stoic approach, they do not need to be harmful. The benefits outweigh the side effects by a wide margin

Perfectionism has many faces. The unhealthy one we develop at school. The healthy one is a natural expression of rational conscientiousness.

Perfectionism and other aspects of conscientiousness are plastic
Personal anecdote. Why use anecdotes?
Interestingly, giving up on obsessions is often very difficult. Two most painful changes of habits in my life were probably: (1) giving up on playing music in 1984 (to save time for study), and (2) giving up on weekly half-marathons after 20 years of uninterrupted routine. Those half-marathons were remarkable for the same route independent of weather or injuries. However, as civilization ruined the pristine route, I was forced to change. I opted for more repetitive sports in line with uniform schedules usable in Plan. This means shorter distances, more often

E: Extroversion

A healthy mind is never extrovert or introvert. It adapts. I explained my point previously: Are extroverts more creative?.

Here I will only tell my own story that ultimately made me write the present text.

Personality test questions are unanswerable:

Personal anecdote. Why use anecdotes?
A few years ago (2018), I played with Eysenck Personality Questionnaire. I was curious how I might score. One answer kept popping up over and over again: "it depends on the time of day". Could a "most cited" psychologist mis-conceive his test (Hans Eysenck)? The clarity of the flaws of the test might have come to me from the fact that I religiously free run my sleep and have developed a uniquely regular circadian cycle that favors biphasic life. I see that few people stick to this kind of "circadian religion". This results in lives that are more chaotic and harder to study. Psychology might reflect this fact. How can I possibly answer the question "Do you like to talk?". In the morning, I never open a mouth. I am locked behind a sound-proofed door. My connections with the world are severed. I ruminate my own ideas and quickly transition to creative work. On most of days, I might utter my first words at midday or later. And then within a span of 1-2 hours I become a talking machine. I talk to anyone I meet in my sports slot. Today (Oct 19, 2024), after swimming, I spoke to an octogenarian German couple who did not speak English. We mixed four languages to exchange ideas. It was riveting. We spoke of health and longevity. I love to talk. But then again, back at home, I close myself in my own world and might not speak for another 3-4 hours (siesta time). I do a great deal of work late in the night. Most of the world around is asleep. So, I do not talk. On extremely rare occasions, I connect with other continents to discuss important idea relevant to my research, school reform, or SuperMemo. What should then be my answer to the question: Do you like to talk?? It is affirmative, but true only for 1-2 hours per day. In psychology tests, my extroversion comes out maximized, but I spend most of my days "talking" only to myself in my mind

Switching to extrovert mode:

Personal anecdote. Why use anecdotes?
Also in 2018, I watched a couple of Susan Cain lectures (incl. Talks at Google and TED Talk). She made me realize that, along her definition, I am as good an introvert as I am an extrovert (more details here). The only difference is the time of the day, which determines the context, which determines my extroversion. Life would be sad and ineffectual without those two modes of action. My wild guess is that people who cannot cool down their extroverted side may never classify themselves as introvert. Similarly, what we often call a true introvert might just be a conditioned defensive response in social interactions. I do not believe in extroversion as a fixed trait (E). If you believe I am wrong, let me know

You may be suspect of my using myself as an example. However, highly regular circadian cycle is the core component of my reasoning. A good anecdote might be a great inspiration of a new model. My story changed my thinking about personality.

A healthy mind can adapt to both modes: the introvert and the extrovert

A: Agreeableness

Agreeableness refers to just being genuinely nice for other people. Agreeable people are empathetic and interested in others.

High agreeableness is the default characteristic of a healthy and free human. If kids seem reserved in contact with others, it stems from natural caution that develops early in the interaction with the environment that is not always agreeable. The disagreeable environment does not need to be social. Unconducive inanimate environments may also undermine agreeableness.

Among the Big Five, agreeableness is the best and the most intuitive illustration of why personality is largely a reflection of the environment rather than genes. The attitude towards other humans is largely an expression of the experience. People surrounded with love will tend to return love. The abused once are more likely to be abusers.

With maturity, the brain will generalize and classify other humans into categories. Each category will receive its own set of interaction rules. We approach aggressive people will caution, and those who radiate love we approach reciprocally. The classification of humans is instinctive and based on simple pattern recognition, which in turn is determined by experience.

The maturity effect is pretty strong in case of agreeableness. If not pestered by health issues or other adversities of age, older people are generally nicer for two reasons: (1) longer time to learn socialization skills and (2) fewer restrictions on freedom that ruin the fun of life for younger people.

This simple picture is complicated by the fact that brains destroyed by adversities of life struggle to adapt. They may have fewer resources and skills to address socialization as well. A neurotic personality may not be able to fully enjoy interactions with others. This biases adaptation. A person with an injured learn drive (e.g. a result of schooling) is a slower learner. Slower adaptations often meet inferior adaptations and those may undermine natural agreeableness. High disagreeableness may be the first step towards a personality disorder (narcissism, borderline personality disorder, antisocial attitudes (ASPD), etc.).

An essential ingredient of agreeability is one's own joy in life. In sum, when other components of Big Five suffer injury, so does agreeability.

Importantly, agreeability is in a substantial overlap with extroversion. What differentiate the two is that the injury to agreeability leads to towards meanness or aggression, while the injury to extroversion leads to avoiding interaction and maladaptive introversion. Thus, nice and extroverted people may drift towards meanness or introversion depending on the resultant of external injury forces. The default personality trait is then separable on the basis of the injury vector. This dichotomy is analogous to submission-vs-rebellion divergence.

It is easy to notice that agreeability can also easily be ruined by one's own health issues, e.g. chronic pain. In other words, there are many reasons for which our planet is not all smiles.

Scientific literature lists many genetic variants that may affect the adaptability. Elsewhere I mention SLC6A4, DRD4, COMT, MAOA, AVPR1A or OXTR. However, these do not change the basic fact that the vector of agreeability is determined by the agreeability of others. The trait is malleable and it hard to paint a ceiling on agreeability. What may change is how much training is needed to get to a set level of interactive joy as measured by select neurotransmitter levels (e.g. oxytocin, dopamine, serotonin, etc.). Do we really care about such details? If we want to have agreeable populations, we only need to set up free, diversified, and agreeable adaptation environments. If there is a variety of the broadness of smiles, it is secondary.

Agreeableness is a default characteristic of humans raised in agreeable environments

N: Neuroticism

Neuroticism is a tendency to experience negative emotions such as anger, anxiety, or fear.

Neuroticism and intelligence

Neuroticism may have a negative impact on one's problem-solving capacity. However, intelligence may help mitigate the effects of neuroticism by providing better coping strategies in stressful situations. An intelligent person may be better equipped to manage anxiety or emotional volatility (source).

High levels of neuroticism are often associated with anxiety, which can impair cognitive performance. Stress can trigger the release of cortisol, which can impair cognitive functions such as memory, attention, and problem-solving. Neuroticism often involves self-doubt and lower self-esteem. Individuals high in neuroticism may engage in rumination, or persistent, negative thinking about their performance or potential outcomes. This rumination can be mentally exhausting and distract from the task at hand. Individuals who are more anxious may avoid challenging cognitive tasks or educational opportunities, which could limit the development of their intellectual abilities.

Neurotic personality does not serve intelligence

Neuroticism and mental health

Neurotic personality may be the first step towards mental disease.

Neuroticism is linked to lower brain volume in specific areas because of chronic stress and negative emotional states, which are common in neurotic individuals. Chronic stress and negative emotional states may contribute to neurodegeneration, leading to reductions in brain volume. Neurotic individuals, due to their heightened stress responses, are more likely to experience neuroinflammation, which can accelerate age-related brain decline. The pathological process is primarily driven by the effects of chronic stress, and the influence of cortisol on brain regions such as the hippocampus, and prefrontal cortex.

The amygdala is hyperactive in neurotic individuals. While the amygdala itself may not show reduced volume, its hyperactivity could influence other brain regions negatively, particularly those responsible for regulating emotions. With a reduced function of the prefrontal cortex, one may have a harder time inhibiting negative emotional reactions, leading to a feedback loop where neuroticism is both the cause and a consequence of brain changes. Maternal separation and other forms of chronic stress can be used in animal studies to increase emotional reactivity typical of human neuroticism.

Neurotic personality does not serve mental health

Advantages of neuroticism

What is considered positive about neuroticism is a side effect of passion and drive. Neuroticism is associated with emotional instability, anxiety, and vulnerability to stress. It is then generally viewed as a negative trait. However, certain aspects of neuroticism may offer adaptive or beneficial qualities within a population. I do not fully appreciate those aspects, and I quote here mostly what I read from other authors. If there are genes that favor developing a neurotic personality, they are probably having some positive side effects. Vigilance is an example. However, in need, you can be highly vigilant without being neurotic. Being scared may be justified. Attention to detail is also an expression of passion that requires a bit of scrupulousness. Motivation to improve is a universal characteristic of a healthy mind. Does neuroticism increase it? It rather changes the motivation vector. Fear produces a healthy vector. Neurotic fear may produce a skewed vector. Empathy and social awareness are trainable and also highly beneficial. I tend to be empathetic and yet there is no trace of neuroticism in the fact. Artistic expression in neuroticism may indeed differ from the creativity of a cooler mind. Again, I rather tend to see neuroticism as an acquired and not-so-positive characteristic. Polygenetic influences might only modify the trajectory that might have an accelerated course in sensitive people.

Heritability

Twin studies show a strong correlation between genes and neuroticism. This is why nearly all researchers claim neurotic personality is hereditary. In the section devoted to genes, we see that higher levels of methylation at the S allele for the serotonin transporter can reduce its already low expression, potentially exacerbating the allele’s effects on emotional reactivity and stress sensitivity.

However, more detailed analysis of the heredity shows that traits are polygenic, and the genes that can be identified have good and bad sides. In contrast, personality traits are clearly delineated as an expression of personality quality. For example, being open to new experience is generally considered a good thing. We want people to be curious and creative. However, in some cultures, curiosity is unwelcome, while creativity in a classroom may result in ADHD diagnosis.

Similarly, being neurotic is rarely considered a good thing in popular language. At the same time, Big Five is a product of factor analysis on personality description adjectives. If we look at specific genes that favor neuroticism, we may see their positive aspects. For example, increased sensitivity to stimuli may be a distraction in some contexts and a benefit in other context.

It is not personality that it hereditary, but it is the susceptibility to the deterioration of personality in set circumstances that may be strongly influenced by gene variants!

From each parent we get a big bunch of genes that may modify the developmental trajectory that shapes the personality; however, it is a safe to say we are all born with qualities needed to develop a personality optimal for the target environment. It is the environment that shapes that ultimate outcome. All traits are plastic. Some people may be more resilient to change or more sensitive to potential deterioration.

The claims of adaptability by Watson are a motto for this text. Experiments with Little Albert showed how anxieties and fears can be conditioned. This might have determined Watson's thinking. He was able to induce neurotic characteristics in a child.

We are born with a set of genes that provide an excellent ground for developing a resilient personality

Personal experience

Personal anecdote. Why use anecdotes?
I claim to be rather stoic. However, in my own life I can demonstrate a striking example of conditioning a substantial fear and then deconditioning it out entirely.

I was an early swimmer (perhaps aged 6-7). My bro would toss me to water from a diving tower at depths and I would love it. I enjoyed the "admiration of the audience". I had an episode of drowning in the sea at a very young age (perhaps 5-6). While diving passionately, I approached the groynes and lost my ground. I could see the surface of the water coming closer and further while I tried to catch a breath. The beach was crowded and some guy pulled me out by my hand. My mom failed to pay attention. Amazingly, the episode left no scars. I would swim lakes and rivers and jump to water from heights.

However, upon watching Jaws (at the age of 15), I lost that fearlessness. In the sea, I started imagining a shark attack. In lakes, I had memories of a horse head at the dark bottom swarming with eels. I did not want to be dead and swarmed in cold darkness. Those fears keep building up until I stopped my swimming adventures.

Then again, at the age of 42, I started swimming a lot with focus on performance. When my brain shifted from fears to other things (e.g. surviving an exhausting distance), I incrementally took more and more risks, to the point when I totally lost my fear of water. I would learn to combat currents, big waves, cold water, winds, darkness, and even ice. All I needed was incremental approach, regular exposure, and specific goals that take the mind away from the baselessly fearful thoughts.

This loss of fear evolved to a point when dying in water might be my prime risk of death today. A 10B storm in winter feels like a fun challenge. Diving in super-cold water in darkness feels ecstatic. I love scary waters. My openness to experience has always been high. My neuroticism negligible. But for 30 years, I was too anxious to open myself to the exploration of the sea or even a local lake. Cold water is my favorite narcotic drug. It is powerful. I learned and unlearned a significant fear in the course of a single lifetime (in the span of 40 years)

Neuroticism is a side effect

We can now conclude that neuroticism is a result of conditioning or a side effect of rapid adaptation. We can see that it is predominantly disadvantageous. I would then rather stop considering neuroticism not as a trait that serves adaptation. It does not seem to be a healthy product of evolution. I would rather see it as a side effect of our maladaptation to the rapid change of the civilization. Why is it then part of the Big Five analysis? I think it landed there only as a result of its importance and its obvious effect on personality. As mentioned elsewhere in this text: Big Five is just a word game. If depression was not included as a serious disorder, it might also land on the personality spectrum.

Jordan Peterson claims that in a neurotic person, complexity may trigger anxiety. This conditioned response is the effect of schooling. At school, complexity is not there to be tackled with reason. It is to be tackled at speed on time. It is a race. You do not get rewarded for solving problems if you solve them too slowly. If you fail in the race, you get penalized. Soon you may recognize complexity as a predictor of penalty. As modern life is full of complexities and deadlines, school is a breeding ground for neuroticism (see: 100 bad habits learned at school).

Peterson adds that if you are unlucky to experience a mismatch of temperament and environment, your life will be miserable (source (after 4th minute)). He is right. The mismatch will leave you neurotic. However, he should rather say that dramatic changes in the environment with insufficient adaptation time may result in a slide into neuroticism. This should rather be seen as a pathological side effect of a failed attempt to adapt. You can easily avoid the mismatch if you begin your adaptation early and with no time constraints.

Traumatic life events can also have similar side effect: death of a spouse, a parent or a child, loss of a job, divorce, homelessness, etc. More often, however, a childhood with limited freedom is enough to limit adaptability.

Peterson notoriously overestimates the power of the gene and underestimates the beauty of the life on the planet.

Neuroticism is a byproduct of the rapid changes introduced by modern civilization

Unschoolers

When I speak to young unschoolers, or kids who approximate unlimited freedom of development, their answers to my personality test questions are invariably the same: "it depends". It is a great expression of the flaws of the Big Five approach and its genetic bias.

Let me here list only a single example of adaptability per trait:

  • O: curiosity depends on the domain
  • C: conscientiousness depends on the priority
  • E: extroversion depends on the social context
  • A: agreeableness depends on the individual engaged in the interaction
  • N: neuroticism depends on past experiences for the context

The main difference between a young unschooled personality and an average adult in modern western societies is lack of schooling. This ensures that all control mechanisms responsible for shaping the developmental trajectory are unaffected by coercion. The main effect of coercion is the suppression of natural instincts that drive the personality in an unhappy direction. In terms of Big Five, unfree individuals are more shy, more perfectionistic, more introverted, unkinder, and more anxious (see: 100 bad habits learned at school).

I have been lucky and free for my entire life. My self-observation helps me see my own plasticity. I can be all kinds of people depending on the context. Even a degree of neuroticism has its place and advantages. Self-observation was also the starting point for this entire text. Too many claims from psychology books disagreed with my own observations and research.

Plasticity of personality is a reflection of mental health

Missing heritability

Where are those genes?

Turkheimer noted that the study of the genetics of personality began with a tremendous promise, but ended in frustration, leading to the concept of missing heritability (Turkheimer, E. (2014). The genetics of human behavior: Lessons from twin studies. Current Directions in Psychological Science, 23(4), 273-278).

The term missing heritability refers to the gap between genetic variation identified in studies and the actual heritability of traits observed in populations. It arose from studies on various traits, including those underlying personality. Researchers discovered that common genetic variants accounted for less heritability than anticipated based on insights from twin studies.

In 1996, a furore was caused when dopamine D4 receptor was found to be associated with novelty seeking. Soon neuroticism was associated with serotonin transporter gene. It was the beginning of a new era in the study of personality. Sadly, soon the replication crisis hit. Even the proponents of genetic roots of personality admit that candidate gene research turned out to be a blind alley (see: Why Is Behavioural Genetics A Hated Science? - Dr Stuart Ritchie).

Large-scale genome-wide association studies (GWAS) analyzing millions of SNPs identified only two SNPs associated with curiosity and one with conscientiousness, together accounting for just 0.2% of the variance in these traits.

Is it possible that certain genes, unrelated to personality, still have an influence on it? For example, a gene that causes a minor mutation leading to digestive problems in infancy could have a downstream impact on personality. If this digestive issue affects the baby’s mood, sleep, and interactions with caregivers, it could set off a cascade of environmental and psychological factors that increase the risk of developing certain personality traits, such as neuroticism. Could we then consider that mutation a personality gene?

In this text I try to explain the origins of missing heritability. Most of all, I try to show that despite being polygenic, the ultimate personality outcome is indetermined. We can help people grow lovely dispositions independent of their genotype.

Genetic symphony

A massive impact of similar genes contributes to missing heritability. The problem arises because the genetic variants identified in genome-wide association studies (GWAS) often explain only a small fraction of the heritability estimated from family and twin studies. This discrepancy suggests that there are other sources of genetic influence that GWAS might not be capturing effectively.

Personality traits are likely influenced by a large number of genes (polygenic influence), each contributing a small effect. Many of these genes might not have direct effects on personality but could affect related biological processes that influence personality indirectly. When the effects of many of such genes accumulate, they could significantly shape personality traits, but each individual gene's effect might be too small to be detected in GWAS.

Polygenic height scores correlate strongly with actual height because they aggregate the effects of numerous genetic variants contributing to height. Polygenic scores may also determine the risk of diseases such as coronary diseases or diabetes. In those risk cases, nutrition and exercise can cover up for most of the difference. The same is true in reference to "nutritive environments" that foster sunny personalities, high intelligence, and pristine mental health.

Genes with indirect effects might interact with environmental factors in complex ways. For example, a gene that affects early childhood health might influence personality development through its impact on life experiences and social interactions. Such interactions are difficult to capture in GWAS, which typically look for direct associations between genetic variants and traits.

Genes that impact personality have pleiotropic effects, meaning they influence multiple traits. A gene involved in a biological process like metabolism might also influence mood, stress response, and, indirectly, personality. These pleiotropic effects might dilute the apparent direct relationship between a single gene and a specific personality trait, making it harder to detect in GWAS.

Genes that regulate other genes (e.g., through epigenetic mechanisms) could play a significant role in shaping personality traits. These regulatory genes might not be directly associated with personality in GWAS but could influence the expression of other genes that are more directly related to personality traits. An example of a gene activated by environmental interaction might be a dormant predisposition to schizophrenia that responds to environmental factors such as chronic stress or amphetamines. The suppression of resilience-incurring gene occurs via methylation of histones occurring in the hippocampus (source). This epigenetic regulatory network complexity could contribute to missing heritability.

Rare genetic variants and structural variations (like copy number variations) might have substantial effects on personality but are often missed in GWAS, which typically focus on common SNPs. If many rare variants with small effects are involved, they could collectively explain a large portion of the heritability.

The missing heritability problem comes from the complex and indirect effects of many genes, which together have a substantial influence on personality. These indirect effects, gene-environment interactions, pleiotropy, and other genetic mechanisms might not be fully captured by current GWAS approaches.

Breaking up the determinism

The de-emphasis of genetic determinism is important to eliminate problems such as poor performance at school, mental disease, addictions, and violence.

Kids who struggle with fractions in school are often labeled as "bad at math". Yet, the same kids can excel in building rockets or designing bridges using advanced physics software. Some even explore relativity and quantum theory, learning through YouTube videos rather than traditional textbooks

The old notion of math talent is just one of those old myths of the archaic school system. Tragically, teacher's perception of math talent predicts math scores (source). Those pre-determined paths and school selection are steeped in genetic mythology.

Aware of this burning problem, Oliver James went a step further in his opinion article for The Guardian (here):

Scientists call this the missing heritability. But there are strong grounds for supposing the heritability is not actually missing – it’s non-existent

Illusion of heritability

Individual genes solely responsible for personality traits have never been identified. Instead, personality is influenced by many genes, each with small and often nuanced or contradictory effects (see separate section in this text: Known genes). In polygenic scores, gene variants can interact synergistically or antagonistically. As a result, parents with high polygenic scores for a particular trait may produce offspring with combinations of variants that offset each other, potentially leading to a lower score.

Personality-related genes are pleiotropic. Their effects extend across multiple traits and may manifest throughout the personality spectrum. Lastly, heritability is not an intrinsic property of a trait. It depends on the population and the environmental conditions in which the population exists.

Brain over brawn

Personalities are affected by particularly high diversity. They are particularly sensitive to the impact of the environment. Most of a human machine is adaptable, but the brain is the leader of adaptability. The shape of the bones is malleable. Muscles, bones, and tendons can be strengthened and molded. Skin color can change under the influence of the sun. However, there is nothing more adaptable than the brain. All personality traits come from the brain. Genes have a huge influence on the developmental trajectory of personality, but it is the environment that determines the ultimate adaptation. In nurturing conditions, most kids can reach genius levels of creativity. All people can grow nice or grow nasty depending on their circumstances. Kids from Compton will all be different, but might all gravitate towards high intelligence, high propensity to violence, high creativity, and high assertiveness. It is the Compton milieu.

Adaptability is the root of the diversity of personalities

Harm of schooling

Uniform shared environment, e.g. coercive school will blow up the significance of heritability! In the wild, diversity may be wider, and more environmental.

What is worse, coercive schooling is likely to transform a default curious optimist into someone who has lost his curiosity and social extroversion. School makes people less agreeable and more neurotic. It converts conscientiousness into pathological perfectionism and unhealthy self-discipline. Coercive school invariably changes children for the worse (see: 100 bad habits learned at school).

Research in psychology is based on humans who have been schooled. As such it is terribly biased.

We are born with fantastic brains, and yet, due to schooling, only a few reach the level of genius

Judith Harris

Judith Harris famously argued that the influence of parenting on personality is overestimated, with genetics and peer groups playing a more significant role. This perspective has led to a popular saying:

If you believe in the impact of environment on personality, have another kid, and you will see how kids differ

This is an upside-down conclusion. Family life is an unpredictable chaos of relationships and dependencies. Even identical twins would turn out dramatically different if separated by just 2–3 years in age, as the dynamics within the household and their experiences would inevitably diverge.

Shared environment do not carry shared impact vectors

Non-personality genes that affect personality

A great way to study the link between genes and environment is to observe identical twins separated at birth and raised in drastically different environments. "The Three Identical Strangers" provides a good storyline to see what happens in such cases; except, the kids in question have been separated at 6 months to the detriment of their mental health.

There is a clear correlation between genes and personality. However, genes that are completely unrelated to personality can heave a major impact on shaping personality through the interaction with the environment.

For example, the genes that make for general attractiveness make life easier, and help retain the default personality, esp. by withstanding the negative impact of pathological socialization at school.

Equally important are the genetic traits associated with ethnicity that can influence how individuals are treated in discriminatory environments. The mechanism is exactly the same as in the case of attractiveness as a mere skin color can expose a kid to more bullying, or more favoritism at school.

Those outwardly apparent human characteristics will underlie a powerful link between genes and personality, and no twin study can remedy that. Not only is twin separation unethical, but it is also impossible to find opposite discriminatory vectors without implicit harm to children. It would not be nice to place a skinny kid in a culture that loves round shapes.

Conducting experiments that involve placing individuals in families of different racial or ethnic backgrounds can raise significant ethical concerns, especially regarding informed consent and the potential for harm.

We know many cases of adoption of non-white kids in white families. A more interesting are cases where white kids are raised in black communities (e.g. in Africa).

In there, white children may experience a form of reverse discrimination, if they are perceived as "other" in an African setting. Their skin color can make them stand out and depending on local attitudes toward race and colonial history, they may be treated with suspicion, alienation, or targeted for negative attention. On the other hand, in some African cultures, lighter skin can carry connotations of beauty, and success.

There were rare cases where white children have been adopted by African families. In such cases, white children might still experience a degree of social discrimination related to their skin color when interacting with the community. Missionary families have often lived in African villages, and their children, often white, were raised alongside local African children. The treatment of these children depended heavily on the cultural values of the village and the relationship between the local community and the missionaries.

Ultimately, whether white skin is treated as a cause for discrimination or a source of privilege in African communities depends on the specific cultural, economic, and historical context.

Genes that affect appearance will influence the personality

Divergence in identical twins

Identical twins will diverge in personality based on minor differences stemming from accidental disparate events. One twin may become interested in crime novels, the other in football. Football may favor time outdoors and exercise which will help neurogenesis. This serves well openness and curiosity. On the other hand, crime novels will have a similar but likely less pronounced effect.

Experiment on genetically identical mice shows the divergence in a rich shared environment: How Identical Twins Develop Different Personalities. The excerpt is abbreviated:

Researcher Julia Freund began with 40 genetically-identical young female mice. These mice were housed in a custom-built mouse paradise.

Though the mice at the start all demonstrated a similar level of wanderlust, by the end of the experiment their travel patterns were decidedly different. While some mice hung around a home area, others spent equal parts of time in all the cage’s corners. The mice’s wanderlust at the end of the experiment was correlated with how many new neurons they’d added in their hippocampus.

It’s been known that physical activity promotes neurogenesis, but in this case the researchers found it didn’t fully explain the differences. Mice that were very active but in a limited range showed less neuron-creation than mice that wandered over a greater area. The researchers thus concluded that the mice’s divergent experiences of their environment were driving their brain changes. In the end, about one-fifth of the differences in neurogenesis between the mice was attributable to how far the mice wandered.

Thus identical twins, though they start with the same genes, likely develop different personalities in the same environment partially based on how they interact with their environment. This lived experience, in turn, probably changes their genes: Previous research has found that human identical twins accumulate epigenetic changes as they age, making them more dissimilar over time. In this way small initial personality differences could snowball—changing behavior, which changes brain—and result in our colorful, unique selves

Personality trajectories are chaotic even if the genes and environments are identical

Conjoined twins have different personalities and preferences despite sharing the immediate environment and even their body parts. See: What Twins Can Teach Us About Genetic and Environment Influences

Family cascade

If we could have a set of identical twins of different ages growing in the exact same shared environment, we would see how their personalities shape differently. Depending on the family environment and external environment, the interactions may spread in waves leading to chaos (like waves in a small puddle disturbed by a stone). However, in well-regulated families they often form a pyramidal harmonious cascade. One of the most striking elements of influence is that the younger once have more models to follow and take inspiration from. In conditions of plenty, this is highly beneficial. However, if resources are scarce, the younger ones adapt to scarcity and develop a different but equally rich skillset.

The skillset of the youngest kids at the bottom of the family pyramid might include sociability, risk-taking, rebelliousness, novelty-seeking, playfulness, humor, and high adaptability. However, in conditions of scarcity of attention, they may also be attention seeking. They may also turn out more dependent and pampered.

When kids are born in similar intervals, when the environment is not changing, when they attend the same school, they are a fantastic observation ground showing how a close genetic circle can clearly differentiate personalities due to a different social interaction dynamic.

When getting involved in a school strike in Poland, I had a great pleasure of interacting with successive representatives of the same family. The oldest, out of school, is a model of serenity and conscientiousness. Each of the remaining six brothers showed and increasing degree of opposition to the school system. The attitude of the youngest is rebellious to the point of worry. They all moderate their behavior with age, but I had a great pleasure to see them grow and interview them throughout their primary school years. They alone should be a subject of a scientific dissertation. Looking like twins but sporting a very special personality each.

Butterfly effect

Consider a wildly simplified theoretical model of a developmental trajectory for personality.

If we randomly flip a single nucleotide, in any gene, we may end up with microscopic differences in the way we adapt to the environment. For example, in social groups, a stable equilibrium usually determines an alpha personality (a dominant individual). If two identical twins grow up in a diadic social group, one will tend to dominate, and the domination is likely to solidify over time (e.g. the stronger individual will have better access to food and become yet stronger). Minor genetic non-detrimental flip might result in thinner skin, greater resistance to pain, weaker teeth, etc. One change can determine the outcome. That one "mutation" (genetic variation) might then be hailed as responsible for alpha-proneness! Detrimental changes are likely to be gradually eliminated from the population and are of less interest. This illustrates the butterfly effect in genetics, where a seemingly insignificant genetic variation, in interaction with environmental factors, could lead to significant phenotypic differences. Those variations do not need to be in any way related to the trait or might even produce opposite outcomes in different environments.

Small irrelevant genetic variations can have significant phenotypic outcomes

Power of a gene

A human is considered smarter than a monkey. The genetic differences between a chimp and a human baby make a world of difference. However, within Homo sapiens population, genes have much less influence over personality than is popularly believed. We all form a huge interchangeable gene pool, and genes that do not serve adaptation tend to slowly disappear from the population. Humans are all different, but their adaptability is largely the same.

Twin studies will make you believe that 40% of personality is hereditary, however, if you look for specific genes (e.g. with GWAS), you will find just a handful with microscopic influences. Ironically, of 12,000 genes that contribute to height, each is having an impact on personality.

Diminished height had a huge impact on the personality of Putin. Conversely, Michael Jordan would be a very different person had he been born as short as Putin.

Lives of Danny DeVito (1.47 m) or Shaquille O’Neal (2.16 m) will tell you that despite disadvantages of being very tall or very short, the genes that moderately contribute to height will not be eliminated from the population due to height alone.

Same truths affect thousands of genes that affect personality. If they all conspire to make you neurotic, your chances of passing the bunch to the next generation diminish slightly. We want populations that are diversified via adaptability with lesser variability being advantageous population-wide in identical environments.

There is little doubt about what variations of Big Five are considered advantageous in set circumstances. This is why the population genetics will generally drive towards the optimum default with a high degree of adaptability (see: Are extroverts more creative?)).

Geneticists are adamant that genes determine personality (to a large degree). Behaviorists believe in the incredible plasticity of the brain. I study adaptability, which might make me a tad biased. However, I also study the brain, and molecular aspects of memory. It is memory that determines who we are. It is the brain architecture that determines the impact of memories on personality and behavior. Our current knowledge of the brain speaks a lot of adaptability, and nearly nothing about genetically determined parameters that might sway adaptation trajectory one way or another.

If you ask geneticists and behaviorists about personality, you may get different answers

Heritability does not limit Adaptability

Eric Turkheimer says that in inbred rats you may find heritability of 0, while in rats held in solitude in perfectly identical cages you might find heritability of 1. The most influential "identical cages" in human lives are the "depository" institutions of the youth: daycare, preschool, kindergarten, and coercive school.

By flattening the impact of the environment through coercive upbringing, we amplify the butterfly effect of the genes and increase the illusion of heritability. School seems to segregate humans into genetic categories providing a corset on adaptability.

Turkheimer put is best (source):

Heritability does not constrain malleability (Turkheimer)

However, the environment can constrain heritability. Geneticist Richard Lewontin noticed that in times of plenty, height is highly heritable, while in times of famine, it is largely flattened. In contrast, psychologists such as Arthur Jensen and Robert Plomin consider heritability to be inseparable from the trait.

As individuals grow older, the influence of genetic factors on traits tends to become more pronounced, regardless of the environment. In controlled or restricted environments, individuals are more subject to external influences, which can limit the expression of their genetic potential. Environmental factors play a significant role in shaping outcomes.

When individuals have the freedom to choose their environments, they can align their experiences with their genetic predispositions, which allows for greater expression of their inherent traits and abilities.

The Debunker: Dr Jay Joseph

Jay Joseph is a psychotherapist who is a serial debunker of genetic aspects of intelligence, personality and mental disorders. In his practice, he can see the effects of abuse, oppression and discrimination. This provides rich direct evidence of the power of the environment.

Joseph's opponent, Robert Plomin himself noticed that psychological traits might vary across ethnic or gender groups not because of genetics, but due to factors like discrimination (source):

The causes of average differences aren’t necessarily related to causes of individual differences. So that’s why you can say heritability can be very high for a trait, but the average differences between groups – ethnic groups, gender – could be entirely environmental [Plomin]

Media and textbooks are all soaked in genetic myths that pervade our culture. It is common knowledge that schizophrenia tends to run in families. Joseph found little evidence of genetic predisposition to schizophrenia (see: 'Schizophrenia' and heredity: Why the emperor (still) has no genes)(pdf). He found no reliable evidence from identical twins raised apart in mental disorders studies!

Big Pharma emphasize the genetic basis of mental illness because it allows them to link specific neurotransmitter profiles, shaped by genetics (neurochemical phenotypes), to a clear need for medication, thereby creating demand for their products.

Non-genetic approach to mental disease favors prevention and behavioral therapies over drugs. A skeptic might argue that the non-genetic interpretation of personality serves the interest of a psychotherapist (except Jay's evidence is rock-solid).

Vested interests of Big Pharma, psychotherapy, etc. contribute to the obfuscation in the nature-vs-nurture debate

Interestingly, Joseph also debunked another popular myth: there is not criminality wired into the genes.

I recommend this fantastic fact-packed interview: No Evidence of Genetics Behind Psychiatric Disorders

Turkheimer vs. Joseph

Turkheimer referred to Joseph as an arsonist during a debate on the role of shared environments in twin studies (source). This critique included a poetic metaphor crafted by Joseph, which, in my view, encapsulates the reasoning of these two brilliant minds at the heart of the nature-vs-nurture debate.

A parable about house fires: Joseph imagines a town in which houses are made out of different kinds of wood, building materials standing in for genes. The town is threatened by marauding bands of arsonists, representing environmental threats. Civic leaders waste time computing flammability coefficients representing percentage of fire variance accounted for building materials, while giving the arsonists free rein. The book [The Trouble with Twin Studies] closes with a plea to mind the arsonists who are the real threat, the leverage point where something can actually be done. It’s a nice story, but do you notice something? It completely undermines Joseph’s own argument. I mean, if you lived in a community under constant threat from arsonists, mightn’t you have some interest in a house made of relatively fireproof materials?

Metaphorically, both thinkers are correct, though they approach the issue from different perspectives. Joseph focuses on the practical support he can offer his patients, particularly in countering the threat of "arsonists". Turkheimer, on the other hand, seeks to understand the role of genes—metaphorically, the "building materials".

For parents and educators, the primary concern is the risk of "arson". Every day, brilliant minds and personalities are lost to arsonists disguised as benefactors: institutionalized childhood, school coercion, authoritarian parenting, and the pervasive influence of "modern" life, all of which disrupt natural development.

In education, we focus on maximizing everyone's potential. Genes are only a curiosity

Developmental unpredictability

If science says there is a 40-50% heritability of personality traits (with all Big Five contributing to a similar degree), the science is right about numbers. Genes and traits correlate. But the conclusion drawn from numbers is dead wrong. It is highly misleading to say, "personality is hereditary". It is more accurate to say that, to a microscopic degree, genes nudge developmental trajectories. Personality is entirely plastic (in free and rich environments). It is only that the exact same environmental influences may result in significantly different outcomes.

Using a spaceflight metaphor, genes act like microscopic thrusters, subtly guiding the developmental journey, where even the smallest adjustments can lead to vastly different destinations.

Given a precise genotype, we have nearly no way of predicting the outcome of personality development

Known genes

In a cognitive contest between humans and apes, humans usually win when employing human criteria. The difference between the two groups is hidden in the genes. However, in contests between humans, genes play far less a significant role.

A gene variant or a non-deleterious mutation can modify the adaptation vectors. This means that an adaptation trajectory may differ between individuals. Some may adapt slower but are more able to reverse the course. Others become very rigid once adapted. Yet others show fantastic plasticity despite multiple adaptation efforts. The value of a given vector shows up only in a subset of circumstances. This way having a large variety of adaptation trajectories, humans can successfully inhabit multiple adaptation niches. We differ. But we all have all necessary adaptation capacities in the cognitive sphere. If not limited by physical or organic factors, we all learn to walk, speak, count and read. We can play chess, enjoy music, or learn programming. We can be nice or mean. It is all a matter of adaptation and adaptation is the effect of exposure over time.

For example, a tiny genetic variant may make one slide faster into neuroticism or introversion or aggression. However, the variants only change the adaptation targets if environment sampling is possible. They also change the adaptation trajectory, which can outwardly be seen mostly as adaptation speed. Genetic variants do not deprive individuals of adaptation options. The brain is universally plastic and this affect personality as well.

Genetic variants modulate adaptation trajectories. They do not block adaptability

Heredity factor

Around 1 in 50 people are affected by a known single-gene disorder. Approximately half of the population will experience some kind of health problem rooted in genetics over the course of their life. In other words, not everyone is "perfectly healthy" at conception. At birth, around 1-2% of people may have an organic defect in control systems that affect personality or behavior.

This suggests that the optimistic message of this text may not fully apply to as many as 3-5% of children. When a child exhibits signs of neuroticism or other challenges from birth, their path to adulthood may not be as bright as portrayed here.

Variability at birth is less likely to be caused by genetic variants of normal genes and more often the result of deleterious mutations. More commonly, however, such outcomes are shaped by maternal stress, trauma, infections, poor nutrition, disease, toxic exposures, or other factors during pregnancy that can lead to developmental issues or birth defects.

A small proportion of kids are born less fortunate, and may find it harder to thrive

Eugenic origins

As I write these words on Oct 7, 2024, Donald Trump rants about immigration that brings in "thousands of murderers" to the country, with an emphasis on the claim that "murder goes in the genes". This illustrates the potential harm of the theory of personality genes.

Trump's claims about immigrants "poisoning our blood" is part of a long tradition of eugenic rhetoric that dates back to Henry Goddard (1912). With his interest in IQ, Goddard "pioneered" precise classification of "morons, imbeciles and idiots"! By his account, roughly 80% of immigrants were feeble-minded (incl. Jews, Russians, and the like).

Goddard sought to apply Gregor Mendel's principles to human traits, including intelligence. Goddard's research on the so-called "feebleminded" fed into a broader fascination with the idea that undesirable traits, such as low intelligence, criminality, and even promiscuity, were inherited. This pseudoscientific belief laid the groundwork for social policies that targeted immigrants, particularly from non-European countries, as genetically predisposed to criminal behavior. Trump's rhetoric echoes these earlier ideas by suggesting that criminality is a genetic trait carried by certain groups, reinforcing harmful stereotypes that have been debunked but still resonate in political discourse today.

See also: Myth: Blacks are less intelligent than whites

Polygenic nature of personality

While it is difficult to identify individual genes that affect personality, polygenic analysis has shown that more and more loci are correlated with individual traits, mental disorders, or intelligence.

Single genes rarely explain complex traits like personality or intelligence. Instead, polygenic analysis, which examines the combined effect of many genes, has found increasing numbers of specific locations on genes that are associated with these traits. The effect of any one locus is usually microscopic, and environmental factors play an oversized role.

We have already discovered a connection between genes and ... dog ownership (source)! Genetics explain more than half of the variation!

Personal anecdote. Why use anecdotes?
I wonder what my genes say about dog ownership proneness. As a kid I madly wanted to have dogs. I took many strays from the streets to my household. I also kept dozens of other pets from all classes of vertebrates. Today, I insist I absolutely cannot afford a dog. I sense no yearning. Which me lives in my genes?

In the end, as research becomes more precise, we may conclude that through the butterfly effect, all genes play some role, and polygenic scores are a form of phenotypic pattern recognition, with a distant connection to Mendelian genetics.

Nathaniel Comfort phrased it perfectly (here):

If all you have is a polygenic score, everything looks like a gene!

This justifies the claim that genes affect personality, but the practical meaning of polygenicity is that we should focus on environmental influences, and their impact on the health of society. We can debate nature-vs-nurture ad nauseam, while all solutions to social mental status lie in the environments.

The figure below illustrates the proliferation of genetic links in schizophrenia, which can be contrasted with a horrific early interpretations:

Dispute over schizophrenia's genetic basis has been ferocious. This is hardly surprising given that Swiss psychiatrist Ernst Rüdin — an early proponent of the argument that the condition is a single-gene disorder — advocated the view that people with mental illnesses should not have children, and justified the sterilization and murder of people with schizophrenia source

Figure: We have gone a long way from the single-gene interpretation of mental disease to today's polygenic view. The former was the basis of the claim we should sterilize mentally ill. The latter provides ground for understanding the value of diversity. The figure illustrates the proliferation of known genes that can be linked to schizophrenia. Source

DRD4

Dopamine receptor D4 (DRD4) has long been associated with traits like thrill-seeking, risk-taking, and creativity. Earlier research suggested that this gene might have a profound effect on personality, linking it to novelty-seeking behavior. This would then be the magic driver of the learn drive in humans. It would allegedly separate those more and less curious, and in the long run, those more and less intelligent.

The idea gained prominence in the late 1990s, particularly with a study published in 1996 by Benjamin et al. in Nature Genetics (Population and familial association between the D4 dopamine receptor gene and measures of Novelty Seeking). This study linked the 7-repeat allele of the DRD4 gene to novelty-seeking, which sparked significant interest in the potential for single genes to influence broad personality traits. 7-repeat allele occurs in 1% of Asian, but up to 50% Native American populations (it may have undergone positive selection in migratory populations).

However, newer studies emphasize that while DRD4 may influence such traits, personality is shaped by a complex interplay of many genes and environmental factors. 7-repeat allele might explain only about 3-4% of the variance in novelty-seeking traits.

COMT

The most well-documented and prominent gene associated with personality and intelligence is COMT (Catechol-O-Methyltransferase). The COMT gene encodes an enzyme that degrades dopamine, particularly in the prefrontal cortex, which is crucial for cognitive functions like decision-making, reasoning, and executive control.

The most studied variation in COMT is the Val158Met (rs4680) polymorphism, where a substitution of methionine (Met) for valine (Val) affects enzyme activity. Individuals with the Met variant have lower enzyme activity, leading to higher dopamine levels in the prefrontal cortex. This is associated with better working memory and cognitive flexibility but also a higher risk of anxiety. Studies show that individuals with the Met/Met variant tend to perform better on tasks requiring executive functions, particularly under low stress conditions (perhaps a gain of 1-2 IQ points). The COMT gene is linked to traits like emotional stability and stress response, influencing personality traits like neuroticism and resilience.

While other genes, such as BDNF, DRD4, and APOE, also play roles in cognitive and personality-related traits, the COMT gene is particularly well-documented in relation to both personality and intelligence.

The Met variant is associated with better cognitive performance under low-stress conditions, but under high-stress conditions, the same individuals often experience cognitive overload and heightened anxiety. This is due to the more sustained activation of the prefrontal cortex, which can become counterproductive under stress.

Variants of COMT meet the trade-off between executive function and resilience

BDNF

BDNF (Brain-Derived Neurotrophic Factor) is a protein essential for neurogenesis, synaptogenesis, and synaptic plasticity. Higher levels are associated with faster brain development (which isn't always a good thing; see the precocity paradox). As a result, BDNF plays a key role in adaptability and stress resilience.

The most well-known variant of the BDNF gene is the Val66Met polymorphism, where valine (Val) is replaced by methionine (Met) at position 66 of the protein.

Lower levels of BDNF in the Met variant are linked to reduced stress adaptation, making people more vulnerable to adverse emotional states. Impairments in synaptic plasticity and neurogenesis can lead to reduced hippocampal volume, poorer memory, and a higher risk of mental disorders. In terms of personality, the Met variant may accelerate a tendency toward neuroticism. It's also possible that individuals with the Met variant are more likely to score higher in introversion.

The Val66Met polymorphism in the BDNF gene is relatively common worldwide. Approximately 30% of people of European descent carry at least one copy of the Met allele, while in East Asian populations, the Met allele frequency can be as high as 50%. The allele is rare in African populations.

Genetic diversity within a population is crucial for adaptability. If everyone carried only the Val variant, the population might be less adaptable to future environmental changes. A mix of individuals with different emotional profiles can enhance group dynamics.

My wild guess is that the high frequency of the Met allele indicates its contribution to the value of population neurodiversity.

Cognitive deficits linked to the Val66Met polymorphism are not substantial; memory impairments might account for a 1-3 point IQ drop. When you consider that failing to learn to read can reduce a potential IQ of 120 to zero on a test requiring reading, the Val66Met polymorphism is more of a molecular curiosity than a factor with a significant impact on people's lives.

Variants of BDNF might participate in the plasticity-stability trade-off

SLC6A4

Multiple and sophisticated control mechanisms have evolved to regulate the expression and function of the serotonin transporter. Those mechanisms affect the adaption trajectory in various niches. They may affect how humans interact with the environment in the process of sampling and niche construction. SLC6A4 is a great example of complex regulation and phenotypic outcomes subject to the butterfly effect. No variant plays a deterministic role, and yet in tandem, they serve essential roles in individual and populational adaptation.

Serotonin transporter gene

Altered serotonin transporter expression influences the brain’s response to stress, affecting how one perceives and reacts to stressful situations. People with lower serotonin transporter expression may exhibit a tendency toward rumination and a negative bias in processing emotional information, leading to a more pessimistic way of seeing the world. This genetic variation reflects the broader evolutionary principle that what might be a disadvantage in one environment could be an advantage in another, contributing to the complexity of human behavior, personality diversity, and neurodiversity in general.

Polygenic influences

Serotonin transporter genes have been involved in dozens of expressions of personality and mental health. A great deal of that research suffers from the usual replication problem. However, it is also important to note that each of those expressions relies on dozens if not hundreds of other genes. While we may see correlations, it is hard to build consistent model of the impact of individual alleles. For example, if we peek at the hazy concept of ADHD, we quickly realize it is a polygenic "disorder" due to the effects of genes underlying dopamine, norepinephrine, serotonin, GABA, and other neurotransmitters. Dopamine genes DRD1, DRD2, DRD4, DRD5, dopamine–beta-hydroxylase, and the dopamine transporter. Epinephrine genes ADRA2A, ADRA2C, PNMT, norepinephrine transporter, MAOA, COMT, serotonin genes TDO2, HTR1A, HTR1DA, GABA genes GABRB3, and many others (see the text by Kenneth Blum here for details).

Epigenetic mechanisms

I have already shown that the reasoning that personality is hereditary is misleading. So is the thought that epigenetics turns on specific genes that change personality.

A good understanding of plastic personality can be derived from the general principles of the conceptualization process occurring in the brain in the course of development as well as in the course of learning. Epigenetics is just a mechanism for turning on the genes that take part in modifying synaptic connections and affect the modulation of the activity of existing connections. It is part of the adaptation process in which personality characteristics are a reflection of the adaptation to a specific environment.

Metaphorically speaking, in the process of building bridges as part of improving transport routes in the country, we do not dwell over the production of bricks. Increasing the production of red bricks does not have a direct effect on transportation network of a country. Bricks are incorporated in the infrastructure where they are needed. Genes do not set the personality. Genes serve adaptations.

Short and long alleles

The two main alleles, short (S) and long (L), are associated with different levels of serotonin reuptake efficiency, leading to distinct patterns of emotional regulation. The S allele is generally associated with lower transcriptional efficiency, meaning it produces less of the serotonin transporter protein compared to the L allele.

Individuals with two copies of the L allele generally have lower sensitivity to stress and are less likely to experience mood disturbances. However, they might be less attuned to potential threats or subtle social cues, which could be a disadvantage in environments where social or environmental vigilance is crucial.

Individuals with one or two copies of the S allele tend to have increased sensitivity to environmental stress, often showing higher levels of anxiety, depression, or emotional reactivity, especially in stressful situations. However, this sensitivity may be advantageous in highly social or unpredictable environments where heightened awareness of threats could enhance survival. This allele is also linked to greater empathy and social bonding under supportive conditions.

Variants of the serotonin transporter gene (5-HTTLPR) are generally considered non-deleterious, meaning they don’t typically lead to serious negative health effects. Instead, they are linked to a range of personality traits and emotional responses that reflect an evolutionary trade-off, contributing to neurodiversity.

DNA methylation

DNA methylation is a key epigenetic mechanism that can influence the expression of genes. The serotonin transporter gene, particularly its promoter region 5-HTTLPR (serotonin transporter linked polymorphic region), is one of the best-known genes associated with personality traits that can be epigenetically modified.

DNA methylation on the 5-HTTLPR have been linked to variations in how individuals respond to stress, which in turn affects personality traits such as neuroticism, anxiety, and emotional regulation. People with different epigenetic modifications in this gene may display varying levels of resilience or vulnerability to stress. Individuals with lower methylation and higher serotonin transporter expression often show greater emotional stability and resilience. Higher DNA methylation, often due to stress or adverse experiences, can lead to lower serotonin transporter expression. This is associated with higher levels of neuroticism, anxiety, and moodiness.

Increased methylation may reflect a form of plasticity where individuals become more sensitive to environmental influences. This could mean that the S allele, in particular, shows a heightened epigenetic response to life experiences, potentially amplifying both positive and negative emotional reactions. Methylation of the L allele can also reduce its expression, dampening the expected benefit of having this allele in terms of emotional stability or resilience.

For more details see: Genotype-dependent associations between serotonin transporter gene (SLC6A4) DNA methylation and late-life depression

Chronic stress

Chronic stress, trauma, or adverse childhood experiences can lead to epigenetic changes, such as increased DNA methylation at the 5-HTTLPR region. Exposure to stress increases methylation of the SLC6A4 promoter region, affecting both S and L alleles, though individuals with the S allele may be more vulnerable. This often results in reduced expression of the serotonin transporter, leading to altered serotonin levels in the brain. Exposure to negative social environments, such as bullying or social isolation, can also modulate the gene's activity through epigenetic mechanisms.

Stress does not activate the SLC6A4 gene uniformly across all cells. Instead, its activation is likely targeted to specific brain regions and neuron types where changes in synaptic connections are needed. This localized response is a sophisticated mechanism to ensure that the brain adapts appropriately to stress, potentially altering mood, cognition, and behavior as required.

Maternal care

By analogy, high quality maternal care has opposite effects to stress. It can lead to lower methylation of the SLC6A4 gene, resulting in higher expression of the serotonin transporter, which is associated with more positive emotional outcomes in later life. Over and over again we can see how environmental stressors result in a departure from the default sunny personality, while unconstrained behavioral spaces combined with love, keep the default personality intact.

It is then easy to guess than regular physical activity will result in positive epigenetic changes that may enhance serotonin transporter expression, thereby promoting resilience.

For more see: Daycare misery

Serotonin transporter gene shows how complex regulatory mechanism affect non-deterministic adaptation

OXTR

Genetic variants in the OXTR gene, which encodes the oxytocin receptor, can influence personality traits by affecting oxytocin signaling.

Oxytocin is associated with social bonding, empathy, and trust. Variations in OXTR, particularly SNPs such as rs53576 and rs2254298, have been linked to differences in personality and behavior.

Certain alleles (e.g. the GG variant of rs53576) are associated with higher empathy, better social skills, and prosocial behaviors. In simple terms, they might make it easier to love people in general. Variants may also influence the sensitivity to social stress, with some individuals showing higher anxiety or emotional reactivity. Instead of loving people, we might easily become apprehensive and distrustful. Differences in OXTR can also affect attachment patterns (secure or anxious attachment).

We can see that both agreeableness and extraversion might be affected. However, it is important to stress that all those personality characteristics are adaptable. A kid thrown into a kindergarten when she is bullied will adapt by being hypervigilant and anxious in the presence of contemporaries or people in general. Kids who experience variable reward in the relationship with a mother are far more likely to be insecurely attached independent of genetic variants. Personality of a parent will also play a role, which may obscure the genetic correlation. Most of all, people surrounded with love tend to love the world. My own love of people kept growing with age, freedom and knowledge of the world. In primary school, I loved or admired very few people (mostly within my own family). Interestingly, I seemed to have more love for animals then. My love is an effect of learning and adaptation. Love is rewarding so it is a self-amplifying phenomenon (unless stopped by adversities).

I think that in modern societies, love and empathy should be nearly always advantageous for the individual and the population. It is still possible that in some walks of life, being overly empathetic might hobble someone's efficiency in fulfilling her function. I will not provide examples. Just leave it as a hypothetical.

The speed of adaptation to loving or adverse environments may be affected by genetic variants

MAOA

The MAOA gene is often called the "warrior gene". It encodes an enzyme that breaks down dopamine, norepinephrine, and serotonin. Genetic variants of MAOA can influence the enzyme's activity level. Low-activity variants (MAOA-L) are linked with higher impulsivity and aggression, particularly in individuals exposed to adverse environments like childhood stress. In contrast, high-activity variants (MAOA-H) may be associated with lower aggression levels. These influences are subtle and complex, interacting with environmental factors rather than determining personality on their own.

Again, genetic variants do not determine the final outcome of adaptation but influence its trajectory. These changes can be adjusted over time. In simple terms, adaptation may occur at a slower or faster pace. This variation affects the stability-vs-accuracy trade-off that determines the phenotype at any given time on the course of the trajectory.

The value of variations can best be illustrated with game-theoretical aspects of population evolution. "Warrior variants" can be seen as representing hawks in the classical game-theoretical simulation. However, it is important to note that we are not born hawks or doves. A hawk variant will simply find it easier to adapt to a population of doves.

Doves have no life in a population of hawks. A hawk variant that allows a fast acquisition of the skill of aggression helps adaptation too.

A balance may set differently in a population of humans were culture plays a role in adaptation, and consequently in the evolution. A population of doves may reflect a peaceful future of humanity with harmonious sharing. Hawkish variants may be disadvantageous from the point of view of the population. Doves might then team up to suppress conditions for hawks to thrive. Western culture may play a role. However, one Trump can ravage a million doves in a single run (written on the day after Election 2024 in the US). This will accelerate the cultural revolution that will make it hard or impossible for future hawks to spring a surprise on the population of doves. The remedy is diversity and free learning. It is a well-schooled population that adapts poorly. Compulsory schooling must end

Genetic variants associated with combativeness interact dynamically with the evolution of populations and cultural influences

AVPR1A

The AVPR1A gene encodes the vasopressin receptor 1A, which influences social behavior, bonding, and aggression. Key variants of AVPR1A, particularly polymorphisms in its regulatory regions, have been studied for their association with personality traits. RS3 Repeat Polymorphism in the promoter region is associated with reduced sociability, weaker pair bonding, and less altruistic behavior (short alleles). RS1 Repeat Polymorphism (also in the promoter region) is associated with variations in empathy and sociability. Some research suggests that other SNPs within the gene body may influence traits like aggression, impulsivity, and attachment.

Does it mean that a kid with AVPR1A variants may be born unsociable, unempathetic, or unable to form attachments? The effects of the gene will rather be subtle, and as in all other cases, it will only nudge the trajectory rather than determine the outcome. Perhaps adversity can push an unhappy variant in that poor sociability direction faster, but things like empathy or altruistic behavior come from years of interaction with other people. Positive interactions and rich experiences make us empathetic and ultimately altruistic. I doubt we will ever find a non-deleterious gene that would prevent this scenario.

Empathy and altruism are natural outcomes of adaptation in healthy social groups

APOE

The APOE4 allele is linked to a higher risk of developing Alzheimer's. Dementia has a huge impact on personality. It is an excellent way to simulate how personality injury occurs due to adversities of life (see elsewhere in the text: Alzheimer's disease). However, APOE4 allele rather falls out from the purely non-deleterious category. It likely persisted through evolution due to potential advantages in ancestral environments (brain development, metabolism, etc.). I would attribute its present survival to the fact that the evolution does not seem to care much about older people. As long as genes are spread successfully, the fate of the organism in later years of life is secondary.

DCDC2, DYX1C1, and KIAA0319

When it comes to genetic variants that affect axonal growth, neuronal migration, layering of the cortex, etc. we can safely say that mutations in those genes are an evolutionary minefield. A great deal of variants lead to a degree of cognitive impairment. Intelligence has a powerful impact on personality, but this text is about harmless variants that determine shades and colors of personality. The label of intellectual disability should not be expanded beyond 1% of the population. This text cannot be made universal if we do not exclude the percent of cases that deserve the name "disability".

I would not list those genetic loci if I have not been interested in dyslexia for 25 years now. Many researchers speak of very high heritability of dyslexia. I heard numbers as high as 1.0. Claims of 0.8 are well documented (example). When I first researched dyslexia, I swallowed the "official line" hook, line, and sinker. If everyone labels it as a neurodevelopmental disorder, it must be. However, as my prime focus is learning, adaptation and conceptualization, the more I studied the subject, the more skeptical I was. Imagine my sentiment having learned of educational dyslexia.

Google Scholar returns 1890 publications on the link between DCDC2 and dyslexia. One might think, the case is closed. It takes just one publication to saw some doubt (source):

An intronic deletion within the DCDC2 gene is increasingly used as a marker for dyslexia. Our re-assessment of the literature, however, did not reveal strong support for a role of this specific deletion in dyslexia. We also analyzed data from five distinct cohorts, enriched for individuals with dyslexia, and did not identify any signal indicative of associations for the DCDC2 deletion with reading-related measures

Google Scholar also returns 484 publications since 2020 on the link between KIAA0319 and dyslexia. If the subject is new to you, you may say the mountain of evidence is overwhelming. However, I am far more skeptical of peer-review today than ever.

At the top of my search, I read:

Knocking down the Kiaa0319 gene impaired the primary auditory cortex in rats, resulting in phoneme processing impairment similar to developmental dyslexia

If we dig deeper, we get hints of the origins of the research "avalanche". First, we have a gene identified as associated with a disorder. Then the gene's priority and research stakes increase. The researchers get down to elucidating molecular, cellular and neuronal implications. We may then end up in hundreds of publications in a short time using the same scheme: "Kiaa0319 has been linked to dyslexia" followed by "We found that Kiaa0319 is responsible for the following abnormalities".

This way, valuable findings can inadvertently contribute to the perpetuation of a wrong meme. An example of such a finding might be this:

KIAA0319 KD showed a decrease in the SOX10 + neuroepithelial cells concurrent with an increase in the PAX6 neuronal progenitors and suppression of ensuing neurogenesis. These findings are consistent with a decreased proliferative state at the neuronal progenitor cells due to cell cycle arrest, highlighting the importance of tight regulation of KIAA0319 expression during a critical period of brain development

There is nothing wrong with publications following the said scheme. They all make valuable contributions to science. However, they all fall into the same self-congratulatory mode of contributing to resolving the mystery of dyslexia in abstraction of the actual disorder.

Today, my thinking of dyslexia evolved to the point where I insist: Don't teach your child to read.

Could really dyslexia be so highly heritable while its origins are so clearly behavioral? By virtue of my work and my specialization, I rather tend to question the validity of tools and conclusions of the heritability research.

The bandwagon effect in science may lead to a massive delusion. All models need to be based on interdisciplinary perspectives

I am then adding my cautious perspective. Dyslexia is caused by coercive learning. KIAA0319 is involved in neuronal migration. The link between dyslexia and KIAA0319 might be that variants affect developmental trajectory which affects the outcome of educational strategies and their timing. The rest is up to imperfection of the study of heritability. The practical importance of understanding KIAA0319 for dyslexics is close to zero. The awareness of the variants won't change the optimum approach to learning to read: voluntary acquisition of the skill. Let me then insist again: Don't teach your child to read!

Where's the beef

Having reviewed the most prominent genes known to affect personality, you probably start wondering: Where is the link between individual genes and individual traits? Not only are traits polygenic. All discussed genes are pleiotropic (i.e. affecting many traits). Each gene affects the entire spectrum of personality characteristics.

A wild guess for the best fit of Big Five OCEAN to genes would be: COMT, HTR2A, DRD4, OXTR and SLC6A4. If you read about all those genes individually, you will see that this is a very imperfect fit.

Traits are polygenic. Genes are pleiotropic

Intelligence

Intelligence is excluded from the Big Five family. However, intelligence is an essential component of personality. When we meet new people, we make a fast assessment. We like people who are nice, and when they are nice, we like them to be intelligent. It is all about information, knowledge and cooperation. First, we see if we can work with another individual, and then we assess his potential to contribute towards achieving our own goals. It is easy to see that the learn drive ("openness to experience") is a tool for developing high intelligence. Thus, personality underlies intelligent adaptation to environments.

Unfortunately, the ancient and artificial separation of the rational and irrational excluded intelligence from the concept of personality. Intelligence, allegedly, is about cognitive ability, while personality belong to the realm of emotion. Thus, intelligence may be measured by a math puzzle, while personality by answering questions about oneself.

All thoughts have an emotional color. When I write about intelligence here and I am not cool, composed and devoid of emotion. I am driven by passion, the wish to explain things to myself and to others. A simple test of intelligence devoid of emotion would be to see how I behave if I was interrupted. It never happens, but I bet all the "composure" would be out of the window. I sense I must write these words right now. I seemingly write about cold intelligence, but I am not cold at all.

Even though I tried to reject Damasio's reasoning in my youth, he is right: emotions are essential in decision-making. All my rational world of thought is built with the use of knowledge valuations that are rooted in emotion and provide the food for the emotional life.

It is important to mention intelligence in the context of personality because it is inseparable from personality and undergoes identical adaptation and modulation processes. Interestingly, many psychologists suggested that creativity or emotional intelligence should be part of a personality profile. As much as the learn drive, creativity underlies intelligence. Both are inseparable. Emotional intelligence, on the other hand, is nothing else but a subset of intelligence in the area of emotion. Let me stress again, Big Five is just a word game.

Intelligence defined as the ability to solve problems is highly flexible. When we learn to solve problems in a given field, we become more intelligent in that field, even if we remain totally ignorant of other fields. There is no raw immutable core intelligence that many intelligence researchers seek. The number of neurons, the speed of connections, the energy, etc. These are all domain dependent. We might have brains bigger than the apes and still lose in dozens of cognitive tests just because we have not been trained in certain domains. The speed of a computer matters little if it is not equipped with the right software. The software of the mind is written while learning new things. It gets better with each minute of our lives. It does not help improve our IQ scores we never really care about (see: IQ is a dismal measure of intelligence). Our knowledge software helps us solve problems of the day, and achieve goals of a lifetime.

All the genes mentioned in this text in the context of modulating personality have a significant impact on intelligence. To develop highest intelligence, we need a powerful learn drive (openness to experience). We need to be conscientious about things that matter. Communication with others is usually extremely inspirational. I tried working in a cave many times. I love it. But without the feedback of others there is a limit to how much I can achieve. Perhaps, if you are an introvert, you may accomplish more in a cave? Check it! If we work with others, agreeableness is essential. However, agreeableness correlates with how you feel about yourself. Even on your own you need serenity and a sense of belonging to a bigger entity of mankind, universe or intelligence. Last but not least, neuroticism can ruin the best creative effort. Nevertheless, some neurotic people claim that their fears and anxieties are a great propellant in taking action in life.

In the end, it is easy to show that intelligence is plastic and the formula for high achievement is extremely simple: freedom and peace of mind. There is a caveat though: freedom must begin with the first day of life. If we send kids to school, and they abhor it, they may never return to that dream creative trajectory that was laid for them with their default gene set underlying default personality.

Intelligence determines success in life, and is best achieved by freedom; from the earliest days

Mental disorders

As personality characteristics are plastic, it is easy to see that extreme forms of adaptation or injury will manifest as mental disease. An extreme expression of personality is a result of adaptation that turns out maladaptive (i.e. more trouble than benefit).

The entire value of having genetic variants is to seek the optimum of individual characteristics that maximize adaptations to prevalent niches. Curiosity or agreeableness seem to be always good, but taken to the extreme may verge onto pathological. On the other hand, personality vectors can suffer suppression or injury. One would worry little about the decline of neuroticism, but a total loss of fears may manifest as psychopathy!

Personality injury

Personality injury may result from adaptation to non-adaptation, dysfunctional adaptation, war of the networks, or organic damage such as infection, brain trauma, neurotoxicity, neurodegeneration, and similar conditions.

  • Openness may be lost due to the suppression of the learn drive (e.g. due to coercive schooling). Deficit of the learn drive leads to learned helplessness, apathy, disinterestedness and depression
  • Conscientiousness may be lost and be replaced with negligence and impulsivity (those can be side effects of learn drive deficits)
  • Lost extroversion may become social phobia
  • Lost agreeability may lead to aggression, misanthropy, asocial personality disorder, borderline personality disorder, etc.
  • Eliminating neuroticism seems like a great thing, but the extreme may show up as loss of fears that protect one from harm. It may also turn out dangerous for others (psychopathy). Interestingly, as much as the learn drive can be suppressed, so can fears and anxiety. The mechanism is analogous

Overexpression

At the other end of the adaptation spectrum is getting too much of a good thing:

  • Openness and voracious learn drive may possibly get you to mania, psychosis, extreme risk taking, and the like. This is why so many creative people turn out wild at the old age
  • Conscientiousness may transmute into obsessive-compulsive disorder (OCD) or pathological perfectionism
  • Rampant extroversion may result in behaviors seen in conditions such as bipolar disorder, ADHD, narcissistic personality disorder, etc.. It may go hand in hand with substance abuse
  • I tend to think one cannot be too agreeable, but "people pleasing" can also result in chronic stress, self-neglect, depression, etc.
  • Neuroticism may be amplified towards extreme anxiety, depression, panic attacks, OCD, and more
Extreme cases of personality overexpression or injury will manifest as mental disorders

Alzheimer's disease

Alzheimer’s disease exemplifies how diminished cognitive capacity can lead to deviations from an individual’s default personality. Openness declines as curiosity and engagement with new ideas wane. Conscientiousness weakens, with organization and dependability giving way to forgetfulness and inconsistency. Extraversion diminishes as social withdrawal becomes common. Agreeableness often succumbs to frustration, resulting in irritability or uncooperativeness. Meanwhile, neuroticism intensifies, amplifying anxiety and emotional instability.

Alzheimer's disease shows how the loss of adaptability results in the loss of the default personality

My take

My take on personality is fundamentally different from the established view. We evolved and are born with fantastic personalities that maximize adaptation to niches we have faced for millennia. Those characteristics also serve excellent adaptation to the modern world. However, modern adaptation requires a few preconditions and a bit of caution. I described this all in: Optimization of behavioral spaces in development.

The most fundamental reason why personalities differ, and some do not allow of optimum adaptation is adversities of life that exceed adaptation capacity. In metaphoric terms, throwing a kid at the deep end of the pool rarely ends up in instant adaptation. The worst injury to personality is the loss of openness through restrictions on freedom. In my terminology, humans in coercive conditions adapt to non-adaptation (see: Missile metaphor). The learn drive gets suppressed. The brain is a perfectly adaptable device, and it can also adapt to non-adaptation. For details see: Brain is a perfectly adaptable device. Loss of adaptability due to coercive schooling results in learned helplessness, loss of learn drive, loss of creativity and loss of intelligence.

A brain crippled by loss of openness/intelligence is vulnerable to further injury to personality in other dimensions. It becomes less capable of adaptive conscientiousness. It becomes less capable of employing extroversion in achieving goals. It loses the skills and motivation of agreeableness. It loses the resilience and the ability to respond to stress.

As a result, a person becomes more neurotic, which is the second side of the double whammy. Neurotic people have their other traits disrupted: openness, conscientiousness, extroversion and agreeableness.

By measure of personality tests, openness might be the most stable characteristic (source). If this was the case, it might stem from the fact that suppressed learn drive is a self-sustaining state. Once we lose the pleasure of learning, we lose the most important ingredient necessary to enhance the love of learning (openness): the learning itself. On the other side of the spectrum: love of learning results in more learning and more love of learning. That state might also be stable and resilient in its extreme manifestation.

However, what I speak about is just a tip of the iceberg. Big Five may reflect human language of personality, but it overlooks dozens of other essential dimensions of personality. How about passion and optimism that determine human innovative and executive powers? How about a stubborn drive to achieve one's goals?

Below, I provide examples of personality traits that are inadequately captured by the Big Five framework. Notably, these traits can be cultivated and enhanced through learning and training. This aligns with the central theme of this text: the whole spectrum of personality characteristics is remarkably adaptable. While genetics play a role, its influence is secondary, as traits are shaped by polygenic modulation, with major genes exhibiting pleiotropic effects.

Human personality is plastic, and genes rarely stand in the way of greatness

Important! Personality is not my area of research. However, the glaring inadequacies and misconceptions rife in the field demand some clarification. Instead of seeing personality as a set of traits, we should rather see it as a set of departures from the default optimum. I won't change psychology. However, my point of view might inspire you to revise a few chapters of the book. If you are early in your path to become a great psychologist, please let me know what you think.

Missing traits

Why is intelligence excluded from a personality set? See intelligence for my complaints. If my most outwardly visible characteristic is stubbornness, does it make me disagreeable? Not! Is it an effect of my conscientiousness? Not. It is so deeply ingrained it can be pretty irrational. Why is it ignored by personality questionnaires?

The following list shows how different characteristics intertwine. They depend on each other. Cross-amplify and cross-feed. Instead of using the word game, we need to see those missing characteristics and ponder a different take on Big Five.

Here is just a short list of healthy personality characteristics that are poorly reflected in Big Five. Some come from the propositions of other researchers, others are mine. I leave it in an unfinished and disorganized state as inspiration only. Pay attention to how strongly those characteristics may depend on knowledge and adaptation to specific environments:

  • intelligence, which is a product of the learn drive and one of the most striking and important human characteristics extending well beyond cognitive capacity
  • stubbornness: the key to success, perseverance, and grit. Rooted in reactance and strong convictions based on knowledge
  • rebelliousness: essential characteristic derived from reactance, magnified by the learn drive
  • grit: combination of perseverance, passion, conscientiousness, magnified by the learn drive and intelligence
  • passion: is a reflection of a learn drive dominated by a singular pursuit. Passions are the key to innovation. Passion index might be the most important personality characteristic we would like to have enhanced by education. Coercive schooling brings passion and creativity to the very bottom for most kids
  • perseverance/persistence
  • caution: expression of conditioned attention to risk that depends on the exposure to risks in the developmental trajectory
  • sociability: conditioned set of behavioral rules in overlap with agreeableness and extroversion; reflecting past experiences in social interaction
  • energy: expression of the learn drive, and perhaps a polygenic aspects of general health incl. brain health
  • attentiveness: the ability to focus combined with mental energy and interest might be associated with conscientiousness or with openness. Part of the power of incremental reading comes from boosting attentiveness. It helps by focusing on smaller problems and prioritizing them by the degree of interest
  • affectionateness: the degree to which we love people is a resultant of socialization and experience. Loving people might be the most essential component of mental health and longevity. Loving people helps you feel good on this planet. Hopefully, understanding this text and the reason people differ should help that emotion germinate. Affectionateness is a personality characteristic that makes life fun
  • aggression: the ability to muster combat energy in need
  • stoicism: the ability to take adversities with cool rational minds
  • honesty: conscientious and intelligent adherence to the rules of behavior developed in game-theoretical interactions with social groups (see: HEXACO model)
  • spirituality: the tendency to seek explanations from entities greater than oneself or realities beyond the observed one. Even though spirituality transforms personality, it rather resides in knowledge and is part of the system of convictions. My intrinsically valuable state might have similarly transformative power even though it would not qualify as a product of spirituality
  • sense of humor: expression of intelligence, EQ and extensive knowledge of human psychology. Humor is a way to play with other people's emotions. It is a way to win people to one's side
  • impulsivity: conditioned response to circumstances in which impulsivity brings benefits and an illusion of benefits that might come with escalation
  • egotism: strong focus on Self, combined with reactance, stubbornness, impulsivity, aggression, etc.
  • resilience: the ability to overcome stress in adverse circumstances as a result of resilience training (i.e. optimum and voluntary dosing of stress in the past)
  • optimism: the degree to which we distort the observed reality to see it as better than it actually is. I am a "pathological optimist". This characteristic pervades my personality and my writing. However, I claim it is a good thing. See: Myth: Optimists are less realistic
  • creativity: expression of the learn drive in the right circadian frame given a passionate inspiration
  • drive (need for achievement): drive for achievement is just a subset of passion in which the goals are well-crystallized. It may have a strong social component, as some goals do not seem satisfactory until they are combined with accolades
  • altruism: stems from natural understanding of game theory of life. Altruism is rooted in basic knowledge that makes it easy to see beyond zero-sum gamesmanship. I claim that the acme of that understanding is Intrinsically Valuable State, but you do not need to agree
  • EQ: intelligence in reference to emotions

Further reading



For more texts on memory, learning, sleep, creativity, and problem solving, see Super Memory Guru