Innate

Summary

This book details how our personalities and behavioral traits such as intelligence are influenced by our genes. Mitchell argues that we have traits that are to a certain degree innate and dives deep into the scientific literature explaining how we know that this is true. Yet, the world and especially our brains do not work following simple rules that can be broken down with a reductionist mindset, instead reality is complex and many of the results he presents from the literature are nuanced and surprisingly unintuitive.

Behavior is complicated and how it is influenced by genetics is even more so because genes are engaging in a continuous recursive dance with the environment and the cell that expresses them. Which genes are turned on or off is often due to random thermal noise in our cellular systems as well as signals from the environemnt. All of this is interacting with the program inherent in those genes, altering the outcome, sometimes drastically. Everything is probabilistic, not even the same genome leads to the same result, even if the person grew up in the same family. Monozygotic twins, which share 100% of their genes, still do not produce exactly the same brain. They are very similar but not copies. Even cloning wouldn't lead to the same results, clones would be different from one another, at least a little bit. They would also be a lot alike, just like twins. There are always slight differences and everything that Mitchell talks about in more sweeping terms is population averages. Bell Curves and normal distributions describe traits like intelligence just as much as they do something like height. There is a distribution, that is governed, at least to some extent (sometimes 50-85% even) by inheritance (and therefore some mix of genes).

Main Ideas

Even small differences in brain development can lead to significant individuality. Heritability is a complicated term. It means how much a given trait is caused by or correlated with the same trait appearing in the parents and it describes changes in the variance of the trait within the distribution.

Genes aren't blueprints, they are non-deterministic algorithms that need to be run in a cell and therefore an environment. Genes are therefore not destiny, but instead just part of a greater whole that in aggregate influences who we become as we grow up as humans. Nonetheless, genes do have a–sometimes strong–influence. We know that many mental disorders have heritable components, but how they work exactly is often still not understood. We don't even know how many of the drugs we use to treat mental disorders work either and there is still a lot of work to be done in this whole field. Modern genome wide association studies really help in doing this work.

The way the brain is wired influences how individuals perceive and respond to the world, meaning that no two people experience life in exactly the same way. The spectrum of colors we see, how different senses are linked (like in Synesthetes), how we process mathematics or spatio-visual reasoning, they all have distributions much like height.

Mitchell cautions against overinterpretations of genetic (or really any) research, particularly in areas like education, intelligence, and mental health. He emphasizes the need for a nuanced understanding to avoid oversimplifications and ethical missteps. In this he is very similar to Robert Sapolsky.

All in all, Innate by Kevin J. Mitchell offers a nuanced and science-based perspective on human individuality, focusing on the interplay of genetics, development, and environmental factors in shaping who we are. By emphasizing the variability and complexity of brain wiring, Mitchell challenges deterministic views of human traits and highlights the richness of human diversity.

Detailed Notes

Chapter 1 - On Human Nature

Humans have a nature that is genetically determined to some extent. Some traits are innate.

How can this happen? How can information from genes lead to specific ways that people behave like?

A zoologist studying humans would say they are bipedal, diurnal, gregarious, monogamous, visual, and omnivorous—all of these traits are shared by some other species, but the overall profile characterizes humans.

Human capacities are encoded in genes. There has to be a way of how DNA leads to typical human.

The book isn't about this though. It's about tracing how variations in DNA lead to variations in outcome.

DNA is not a blueprint. It is a program, that when run - within the environment of an egg cell in a mother's womb, leads to an organism. The machinery for running the program and the interaction of the program with the outside world largely determine the result of the program once it has run to completion, i.e. when a fully formed organism is there.

Behavior differences are not excluded from inheritance. We can breed dogs for behavior traits, making them much more docile than wolves.

The details of how genetic differences influence behavior exactly is still not known. Genes act in complicated ways, often changing multiple things at once and at multiple levels of abstraction.

The genome does not encode a person. It encodes a program to make a human being.

Individual experience typically amplifies innate differences.

Chapter 2 - Variations on a Theme

It is difficult to measure something like behavioral traits and tendencies. One needs a number that stays similar for the same person taking the test, that is also similar for people like them, yet different for others. Having these numbers allows to ask more interesting questions.

Twin studies use these numbers to show that genetically similar people are psychologically similar even if raised by different homes.

Behavior traits across an entire population form a distribution. Often normal distributions. Variability can be seen by how spread out a normal distribution bell shaped curve is. Narrow and tall == little variation.

The amount of variance that can be attributed to genetic variation—is known as the heritability.

Brain structure heritability is around 60%. We know this from twin studies measuring brain structure via MRI.

Genes do not stop working after birth, they inform and regulate between organism and environment over the entire lifetime.

Brains are always active, buzzing with default mode network electrical activations. Brain parts only become more active when achieving a specific function.

Spontaneous fluctuations at rest in the brain can be synchronized.

Parenting has a low influence on the variance in behavior measured. Does that mean it doesn't matter? No. Because even if it doesn't change behavioral tendencies all that much, it still teaches valuable ideas and makes children feel better throughout their lives. Abuse is still bad, but doesn't happen often enough to be statistically visible in those studies.

Chapter 3 - The Differences that Make A Difference

Defining what a gene is is tricky because historically it had two meanings - a heritable trait and a section of DNA coding for a specific protein.

Living things are different from non living things because they are organized and actively maintain their organization. Keeping this order up, is work, which is why living things need energy to keep existing. They need metabolism. It also requires information that describes the structure being maintained. This information itself needs to be chemically stable enough to persist. DNA fits that bill. Schrödinger calls such a chemical compound an aperiodic crystal.

DNA - proteins, three amino acids give one codon, determines one amino acid in the chain.

Humans have about 20.000 proteins coding genes, however the genes need to be expressed differently to differentiate between cell types. Not every protein is needed all the time, in every cell. The apparatus that handles gene expression is a highly complicated machine, and attuned to outside factors. Cells can change their gene expression in response to stimuli. Stretches next to protein coding DNA serve as promoters and inhibitors because they help or hinder transcription enzymes to "dock" and read the DNA of the protein. This way multiple molecules interacting with one another can do complex reasoning of when and when not to express this gene or that.

If a cell has only one copy of a gene for a protein, it will only make half the amount of that protein (roughly).

Mutations create genetic variance and that variance gets filtered by natural selection which leads to evolution.

There is a balance between mutation and selection that keeps the human genome generally intact, though at the evolutionary expense of many individuals.

Genes are selfish.

Single point mutation variants for genes are called SNPs - single nucleotide polymorphisms. The human genome has about 25 million such places where more than one genetic variant exists.

Rare, evolutionarily recent variants, can have the most interesting effects.

Even if we can determine the single genes causing hereditary variance for behavior traits like intelligence, that doesn't mean that is all they are. Like the spark plug in a car, they are only one component among many that make up the working system. Genetic hereditary and finding out how it works is non-reductionistic. Especially considering that genes interact with the environment and other genes in emergent loops.

In fact, Mendelian inheritance is rather rare. Genes can have non-clear cut ways of affecting phenotype. Additive, subtractive, only doing something if another gene/protein/molecule is also present etc.

For most behavioral traits these kinds of direct links to the cellular functions of specific genes are not apparent.

Nothing at a cellular level can explain the delusions and hallucinations and disordered thoughts that accompany psychosis.

High level traits are emergent properties

Chapter 4 - You Can't Bake the Same Cake Twice

Trait variance is about more than nature vs. nurture. It is about the unfolding of an emergent system, where feedback loops carry out computation and organize in a way that is affected by random noise. They incorporate noise and control it within certain bounds to achieve fluctuations with order.

Gradients of signaling molecules shape where cells build organs, determining which cell expresses which cell type. The original orientation starts from the entry point of the sperm to determine the coordinate system which the cells use to grow a body.

There are thousands of different types of neurons. Each is morphologically different from the other subtypes. Some sending only few far reaching projections, others being densely interconnected locally and everything in between. Cells in the brain have to migrate to the right places. Neurons literally move around to find the right place to live in order to make the brain work. Neurons wire correctly because of a growth cone, a cellular protrusion that can sense environment chemicals in order to grow in the right direction, towards the other neurons that it needs to connect to. All of this gives us the remarkable effects of learning and neuroplasticity.

There is variation from moment to moment in the precise numbers and positions and states of all of the millions of individual protein molecules and other cellular components that carry out the neurodevelopmental processes.

Genomes can't predict the exact state of a cell in advance, and so genomes don't try. The instructions are variable enough that they can make things work, even with vastly different inputs. The work of Michael Levin on salamander tracts shows this beautifully.

Because proteins have random thermal fluctuations and mediate neural development, behavioral variance has fluctuations too.

Thought: Epileptic seizures are like faulty recursive code reaching stack overflow errors.

We can have traits that are innate but not genetic because of the random fluctuations of our early environment (both inter- and extra- cellular).

Book Recommendation: The Genetics of Brain Wiring - Kevin J. Mitchell

Organisms are robust to perturbations in their environment while growing as embryos. However this robustness is in part depending on genetic fitness, meaning how many major mutations a particular developing individual has. If an individual has many mutations, it is often less robust and therefore if you were to clone it a hundred times, the variance between each of the clones in terms of phenotype would be higher.

Brains come pre-wired, not hardwired.

Chapter 5 - The Nature of Nurture

Brain plasticity is aligning with innate differences to amplify differences in behavioral traits. We are like we are because we construct our environments that influence us and our development, because of the brains that we grew because of our genetics and random fluctuations. We have innate but non-heritable makeups of personalities.

The brains main job is to change itself.

Early childhood trauma leads to adverse effects on brain development. The problem with any claim like this is the data. There is data with correlations but the data is often not sufficient in determining the causal patterns.

Processed of brain plasticity may reinforce and even exaggerate the widespread initial differences that arise due to both genetic and developmental variation.

Through feedback mechanisms neural pathways reinforce each other in such a way that we become very good at processing only the stimuli that matter to us. Our brains are sense-making machines with the purpose of extracting patterns that help us survive.

We can first find all kinds of patterns, then we optimize and exploit those patterns, but lose the ability to rapidly find new ones. This is the typical state of cognitive development, where it gets harder to form truly novel concepts as we get older. Language learning and phonene recognition is a good example of this.

The process of developing expertise to sounds in one language eventually closed off the ability to distinguish between sounds that are not heard as often.

The subjective experience of the environment matters. How we feel about situations matters because it reinforces or inhibits behaviors and these feelings have innate components.

Feelings add meaning to behaviors and internal and external states. Things have valence to us.

We only learn from things that are good or bad for us. If something lacks valence we won't learn it. If rewards feel better to you, this will alter the decisions you make, the behaviors that you form. It will make you more likely to become addicted.

When we self-adapt in this way, we reinforce initial tendencies. If we like music, we tend to seek out more music making environments and become enmeshed in this sort of environment. The same is true for anything else too. You choose an environment based on your preferences and in turn your environment further shapes your behavior and preferences.

How parents treat children is influenced by innate tendencies the child already has. This can reinforce traits in the child further.

Pairs of MZ twins have significantly more similar life experiences than pairs of DZ twins.

Shared genetic heritable variance increases with age. Because the initial effects compound. Somebody just slightly more attuned to liking absorbing of new knowledge likely lives in a house where learning is valued, they also get better grades and positive reinforcement by teachers and find learning itself more interesting - all of which works together to amplify the initial genetic difference over time.

The same ideas hold true for culture and gender differences.

Cultural expectations may arise and persist due to real biological differences between males and females, but they may also contribute to a self-fulfilling prophecy, in that those expectations shape the experiences of boys and girls, offering them different types of experiences and opportunities, which will thus tend to amplify the initial biological differences.

We inhabit the "cognitive niche", constructing and adapting to our own environments through our delayed and long term brain maturation. We are a beginning of infinity.

We gradually become ourselves.

We can't have runaway positive feedback loops forever—we have to maintain these neural configurations to remain ourselves.

We switch, from learning how anything works to being really good and efficient at applying our learned patterns. Changing significantly later in life is difficult.

Developing humans become increasingly crystalized versions of themselves. – Marc Lewis

Chapter 6 - I, Human

Language describes personality traits, there are 8000 words in English that are devoted to this. However many of these are redundant and the real number of different personality trait dimensions is much less. How many is currently still debated. Some models have 5 (Ocean) others have 16 (Raymond Cattell).

Big Five: Openness - how much do we seek novel experiences Conscientiousness - how organized are we Extraversion - how much do we want social stimulation Agreeableness - how friendly, cooperative and helpful are we Neuroticism - how do we deal with stress, how likely are we to get depressed or anxious

Just because we can identify and group personality into these different dimensions doesn't mean they have to exist in reality. They could be an artefact of language or of how we look at things. However a few of the Big Five Dimensions have equivalents in animals too. At least big five tests have a test retest score of 0.7 and agree with how others describe a person too. But whether or not they have real biological underpinnings still remains to be answered.

The reality of how personality traits are inherited is messy and complicated. Personality traits as a whole are up to 70% heritable in variance though. Shared family environment doesn't have a influence.

Genome Wide Association Studies look at the whole genome and potential correlations between certain traits, like Neuroticism and genetic patterns that go along with it. Usually they use the DNA to personality type pairings of several tens to hundred thousand people to get the statistical significance to make claims. What these studies showed is that there is no clear genetic "marker" for psychological traits.

Problems in other methods are exploratory approaches, p-hacking, lack of replication samples and publication bias. Many of the studies that did find something fail to reproduce.

That we don't have findings there means something though: Personality can't be easily mapped into easily defined neurochemical pathways or brain region or circuit organizations. They are more complicated.

If we were to write programs for robots, that give them valence states for different things in their environments they would need to be able to weigh between them, how much risk they are willing to take for getting food for example. This weighing of different factors against one another resembles personalities very closely.

Emotions are heuristic signals that help the brain make close to optimal decisions with insufficient information.

Neurotransmitters play a role in the underlying lower level details of personality. Personality higher level constructs are made out of parts. Novelty salience, delay discounting, confidence threshold, punishment sensitivity, harm aversion and threat sensitivity, all feed into an idea like impulsivity which in turn affects higher order concepts like extraversion, conscientiousness or neuroticism through different behaviors that it makes more likely.

We know that neurotransmitters do this, because we can excite neurons that respond to only certain neurotransmitters aritificially, using optogenetics, this way controlling mid-level personality concepts such as impulsivity.

Serotonin signaling is a component of cost assessment and harm aversion. Low serotonin signaling equals high impulsivity. It also helps unlearn.

This is all messy and complicated though, because the same chemicals play different roles in different brain areas, making the effects of genetic variations extremely hard to predict or even specify. Also the levels of neurotransmitters affect how the brain develops and changes in one neurotransmitter are often counteracted or accompanied by further changes of other neurotransmitfers. All of this further complicates the picture.

Collectively, these results highlight the complexity of the biochemical and neural systems involved. There are many, many proteins involved, expressed in different combinations in different cell types, and their functions interact in unexpected ways.

Sometimes genetic mutations can have strong effects on personalities, to the point of creating personality disorders. People with the wrong variant of the MAOA gene are hyper aggressive as an example.

While we might like to try and pigeonhole different genes into specific roles, we're really fooling ourselves. Nature is under no obligation to make things simple and easy for us to understand.

Brains are sensitive to random noise while they develop, changing the way they develop. This interplays with genetic differences and then builds on top of itself, because the initial differences get amplified because they change the behavior of an individual which leads to a different set of experiences that reinforces the initial difference.

We really are born different and, in many ways, we get more so over time.

Chapter 7 - Do You See What I See?

When I see a red apple, is the quality of my experience the same as yours?

Perception is active. We infer what is out in the world by comparing it to what we expect, which is informed by what we have learned in the past.

Determining what caused our perceptual stimuli is known as the inverse problem, and it is under defined, which means there can be a myriad of causes for the same set of stimuli and our brains have to make educated guesses, based on past experience. We expect the world to be a certain way. Sensory illusions show that this is the case and also give a glimpse into how we do perception.

Vision extracts higher and higher concepts by deeper and deeper layers of neurons in the visual cortex. The first layers conserve spatial orientation. Neurons close by are active when areas on the retina close by are active. It is interesting because deep artificial neural networks (especially CNNs) work in the same way these days. Seeing though, doesn't happen in any of these steps. Instead seeing happens when we compare the representations to the models of the world we have learned in the past. The information flows two ways, up from the lower level areas and down from the expectation areas (prefrontal cortex). We update our internal world models if they don't match what we see through the stimuli we actually receive. Sometimes our learned conceptions of how the world should be are so strong, that our model fails to update and we see things that are not there. This underlies optical illusions. We disregard the actual information coming in to some degree, superimposing our own model on top, forcefully fitting something that doesn't fit.

Perception by doing this is inserting purpose into the signals.

Different species have vastly different sets of experiences because their sensory inputs can be so wildly different. Even the makeup of vision is different because the cells on the retina can be sensitive to different wavelengths etc. allowing for seeing more or less colors than we do. There are also a bunch of senses that we can't even begin to comprehend. Also the valence attached to certain stimuli is vastly different too, some things that we discern as good might be horribly bad for other animals and vice versa.

Taste and smell receptors have genetic variants in humans. We literally have different abilities to detect odors and tastes. Some people can literally not taste something that we could.

Some woman can be tetrachromats because they have four instead of three different working versions of rhodopsin molecules in their retinal cells, this is sort of the opposite of male color blindness.

This shows that how and what we perceive can be altered by our genetics and this means that there are almost certainly variations in how sensitive we are to certain stimuli. Some people might feel cold more strongly, others respond stronger to sounds, others might feel more pain etc.

Perception is a skill—one that we get better at over the first few years of our lives and beyond.

Book Recommendation: The Man Who Mistook His Wife for a Hat.

In people with disorders, such as face blindness or tune deafness, the processing areas for the stimuli often work alright, however the conscious perception is lacking. They don't form the percepts that normal people do.

Synesthesia and it's different forms are interesting, weird.

In the same way that we know that something that with the shape "A" is associated with certains sounds, people with letter-color synesthesia also know that it is red, or blue, or chartreuse, or puce.

Book Recommendation: Inquiries into Human Faculty and Its Development - Francis Galton

Book Recommendation: Speak Memory - Vladimir Nabokov

Book Recommendation: Wednesday is Indigo Blue - David Eagleman

Synesthesia seems to be a single point mutation variation in most cases, genetically. There are different mutations for different types of Synesthesia. Most likely the genes are involved in how different cortical areas are linked to one another leading to the mixing of percepts between different senses. However those are probabilistic, which means that the specific exact type of synesthesia might be random. Sometimes the links are informed by the environment even! Synesthetes who grew up in the 1970s in the US are more likely to associate the colors of the letters in the alphabet with those of a set of a fridge magnet alphabet toy set.

We don't understand Synesthesia fully though. Some people show activations in the areas we would associate with the percepts, some don't. Some lose their synesthesia when under SSRI drugs, others don't. We simply don't know the details yet.

Genetics affect our perception of the world.

Chapter 8 - The Clever Ape

Innate intellectual differences exist. That doesn't mean intelligence is fixed it's just that we start from different positions.

Genetic differences make humans smarter than other animals. Paired with language intelligence is the decisive evolutionary advantage enabling us to live in and create our own niche - the cognitive niche. Because intelligence is genetic (we have it, animals have it less) it would be surprising if there is no genetic variation to it. Genetic variation is about the potential for intelligence, not absolute values though.

IQ tests (and other psychometric tests) are designed to figure out the intelligence of a person. Stanford-Binet test is still widely used. Results of these tests are correlated and predictive of life outcomes to an extent.

Effects of mutations that mess up brain development form their own distribution in IQ scores. They are genetically different from the general factors determining intelligence!

Nurture has effects on intelligence, but those effects are not active across the long term. The genetic effects persist though. In adults intelligence is 75-80% heritable, and there is no family environment component. For intelligence in adults it didn't matter where you grew up only who your parents were genetically.

IQ averages increase, but not due to a change in genetics. The environment causes this Flynn effect. Education and better nutrition are most likely the causes.

There are genetic variants that decrease intelligence. The ones found so far play a role in neurological development. It seems to be the case that there are no positive genes for this, all the variation seems to come from variants affecting the brains development suboptimally. This indicates that intelligence is a function of brain structure, not of it's inner workings. Global network efficiency is the important correlate to intelligence.

Book Recommendation: The Little Book of Bathroom Philosophy - Gregory Bergman

Genius might not be genetic and isn't covered by IQ tests at all. It might simply arise due to phase transitions, triggered by random noise in neural development in already smart people. We simply don't know.

Chapter 9 - Ladies and Gentlemen, Boys and Girls

Sex is a core part of reproduction, it needs specialized cells to fuse with other cells of another organism, and hence a split occurs, one cell is receiving the other, which gives rise to the two sexes. Furthermore, the mobile cell has evolutionary pressure to become smaller, whereas the other one can increase in size + machinery that it brings to the table, which creates an imbalance in the amount of resources put into reproduction. Organisms who mate, need to find out with whom in the world they can mate, they need to make choices. From this follows that there is a difference in how stringent that choice is for the different sexes. Females who have more to lose because their initial investment is higher, are usually pickier in their choice of mates. This argument is covered in depth also in the books The Selfish Gene and The Red Queen. The pickiness of females can drive evolution because of sexual selection, markers that signal genetic fitness are preferred and lead to all sorts of absurd things, like the tail feathers of a peacock. Often males compete for females. This leads to sexual dimorphism, where different sexes of the same species look vastly different. The exact level of variance depends on the mating strategy of the species. Pair bonding vs. alpha male.

Men also have thicker skulls, especially in the front, which may reflect the fact that we like to punch each other in the face a lot.

This dimorphism doesn't stop in bodies, males and females also have different brains, supporting different sets of typical behaviors.

Brains develop differently in brains because of the hormones that the gonads excrete during development. But even before that genetic expression is different in male vs. female cells because of the extra X chromosome in females. Usually it gets turned off but some of the genes stay on and that alters the gene expression of many other processes. This means there are two separate, distinct (albeit interlinked) developmental programs in organisms that have sexes. Brain structure also differs so much between humans that you can predict the sex of a person only from their brain scans with something like 90% accuracy. Also these differences fall onto distributions, just like height. Male brains tend to be larger, more tightly connected locally, but less tightly connected across brain regions.

Brain differences are as innate as innate can be. They are even already starting to be visible in infants just weeks after birth when their brain only reached 35% of the size they will have as humans.

The important question is what do all these differences in structure mean?

Evolution has a tricky job to do—it has to make male and female brains different enough to drive appropriate sex-specific behaviors, without impairing general behaviors required for survival of both sexes, which may involve the same brain regions.

We have no clear idea how differences in different brain regions alter behavioral effects. We don't really have an idea at all how the two are connected.

It is weird if you stop to think about it that a single difference in chromosomes can alter behavior in most of the population that males are attracted to females and females are attracted to males. The effect is strong and poignant as far as genetic effects go. How does it work?

Sexual differentiation operated by switching between to alternative, even competing, states.

Boys tend to be more aggressive than girls. From an early age on and independent of culture and societal expectations. We still think of boys as more likely to fight than girls, but this expectation comes from the fact that that's what boys typically do, not the other way around.

We expect men to be more violent than women because men actually are more violent than women.

Males tend to score higher in dominance, emotional stability, openness to ideas, assertiveness, sensation seeking. They are more open-minded, assertive, risk-prone, tough-minded, cold-hearted, emotionally stable, utilitarian, open to abstract ideas, they are thing focused and prefer theoretical abstract ideas over social values.

Females tend to score higher on agreeableness, neuroticism, sociability, gregariousness, nurturangr, sensitivity, warmth, apprehension. They are more nurturant, warm, altruistic, submissive, risk-averse, tender-minded, emotionally unstable, open to feelings. They are people focused and prefer social values over abstract ideas.

Group averages like these are small compared to individual differences. Like always. The tallest women are taller than many guys, yet guys on average are taller.

Cultured play little role in these differences because they are preserved across vastly different cultures, with vastly different ideas about what men and women are "supposed" to be. Interestingly, the most egalitarian societies, thinking that men and women are the same, show the biggest differences on average male/female typical traits. One possible explanation is that in places where this is the case, generally conditions are quite good, which means that the genetic programs can run to their completion better. The limiting factor in expression of sexual dimorphism being environmental resources.

Despite the difference in brain size between the sexes, with male brains being on average 10% larger than female brains, there is no difference in average IQ scores between the sexes.

However the distribution is different. There are more males at the ends of the IQ distribution than in the middle compared to females.

There are roughly 2 times as many men with IQ in the range if 140+ than women. However in the low range the ratio is also 3:2. For the upper end it is not quite clear whether these changes are due to environmental or inherited factors.

Thought: If you take this into account, how much of the pay gap between genders disappears? Furthermore if you take into account agreeableness too + time spent rearing children and therefore not invested in career?

Initial differences due to sex will tend to be amplified by experience, as individuals' own choices affect their experiences.

None of this is a case against equal treatment. On the contrary we should treat individuals as such, independent of statistical average fluctuations in traits. Person's are not archetypal, they are unique and this is important when dealing with anybody.

While using biological differences to justify sexism is wrong and harmful, ignoring or denying the existence of such differences can also cause harm.

Chapter 10 - The Exceptions

We know that mental disorders are not caused by demonic possession, vaccines, or cold-motherin styles.

Yet we still don't know how many of disorders actually work, how they arise, why they form, how we could fix them. Most of the drugs we have were discovered accidentally and have often strong side effects.

We have about 70 new mutations on average per person.

Older fathers increase likelihood of mutations in offspring because sperm might already be damaged in the germline prior to conception. Disorders share genetic overlap to some degree because they are related to genetic changes affecting brain development. If your family has a history of schezophrenia, that makes you more likely than normal to develop, say, Autism.

The genetics of disorders are complicated, usually it's hundreds of tiny differences of risk factors of genes that contribute to a disease. Mutations interact with one another.

Low intelligence is also a risk factor/correlated with mental disorders. Overall these ideas and insights show that many different disorders can be explained by the same idea - they are development brain dysfunction. That means that schizophrenia and autism are really part of the same problem only expressing itself differently. There is not really a "genetics of schezophrenia" as such.

Natural selection doesn't care how creative you are, unless what you are creating is children (who survive to also have children).

Mental disorders stay constant in the population even though they are very actively selected against because they keep happening again and again. Mutations keep arising and the brain is a very fickle and delicate machine with over 1000 different genes contributing to its correct development where any number of mutations in it can contribute to a variety of disorders. Many of these disorders also don't happen if the same changes happen later in life, they have to happen during brain development to take effect.

Chapter 11 - Implications

Traits are heritable, but the exact details of how genes relate to phenotype are very hard to trace and more complex in most cases than anyone might have expected. Especially when it comes down to behavior and stuff that has to do with the human brain and psychology. Genetic effects exist, but they are highly indirect.

Most traits will be dominated by rare mutations that wink in and out of existence in populations over time.

Genotype Phenotype correlations are essentially probabilistic in nature due to the environmental and internal noise that affects the development of the organism. We will never be able to predict with 100% accuracy only based of a genotype what a person will be like.

We could have a future where people could select their children based on genetics. This has ethical problems attached to it, namely eugenics and where to draw the line. If someone doesn't want their child to have a certain eye color, would that be ok? What about if they want their child to be more intelligent?

Genetic profiles underly frequency dependant selection. As variants become more frequent or less frequent in the overall gene pool, their respective advantages also change. The doves and hawks examples come to mind. As well as ncases game theoretical demo of evolution.

Groups and "races" in genetics are often not cohesive unless there is a strong factor if selection counteracting drift in the genome by mutation. Hence most attributes vary person to person more than average genetic group to group. Furthermore, specifically regarding intelligence there is no argument that would make sense to increase it only in one group of humans. Intelligence is universally useful and as such should increase equally everywhere. Findings to the contrary are hopelessly confounded with environmental factors, not showing genetic, innate differences but often being presented as such.

Book Recommendation: A Troublesome Inheritance - Nicholas Wade

Book Recommendation: The Bell Curve - Richard Herrnstein

I think the two above are mentioned with a big grain of salt in the book.

Variation in our genes and the way our brains develop cause differences in innate behavioral predispositions—variation in our behavioral tendencies and capacities.

Slates don't have to be blank to be written on.

The fact that there is a physical mechanism underlying our thoughts, feelings, and decisions does not mean we do not have free will.

On the contrary, it means that we can do things for a reason, because we have the mental capacities to represent it, patterns in our brains that have meaning to us and can cause us to act in this way or that. This idea is worked out in much more detail in the other book by Kevin J. Mitchell: Free Agents.

Thoughts and feelings and choices are mediated by the physical flux of molecules in the brain, but this does not mean they can be reduced to it.

What matters is the information content inherent in the patterns of neuronal firing that those atoms represent and what that information means.

The self help industry is built on a poisonous message, you are not good enough as you already are, there is a flaw within you that needs fixing.