It’s Probably Mostly Genetic

In this essay, I will argue that the gap between blacks and whites in the US is almost entirely due to genetic differences. By “gap”, I mean all the race differences in behavior and social outcomes: income, crime, welfare use, single parenthood, etc. This is a strong position, obviously, but I will explain why it is the most reasonable position to take.

I will also argue that most statistical differences between racial, sexual and economic demographics in developed countries are due to genes. Again, this is a strong position, but I believe it is the most reasonable one.

Let me give the general outline of the argument first. It has two parts.

Part 1. Modern civilization has created an environment of abundance. The material conditions of human beings have never been better than in modern, developed societies. Almost everyone has access to adequate nutrition, medical care and education. Modern civilization brings out the genetic potential of individuals. As a consequence, the observable differences between people in the modern West are mostly due to genetic differences or random factors that are beyond our ability to control. Thus, statistical differences between demographics (in which random factors wash out) are almost entirely due to genetic differences.

Part 2. Genes affect the environments that people live in. Different outcomes, even if due to environmental differences, can also be attributed to genetic differences. The genes might not necessarily be in the affected person, but in other members of the demographic category. For example, growing up in a violent household might make kids more violent than they would otherwise be. The same is true of growing up in a violent neighborhood and going to a violent school. Those are environmental factors, but they depend on genes: the genes of parents, neighbors and classmates. Most of the environmental factors that affect outcomes have underlying genetic causes.

At the level of countries, cultural and social differences do matter. For example, the cultural and social differences between Haiti and Jamaica are important in determining the different outcomes of those two countries. The same goes for North Korea versus South Korea, Venezuela versus Colombia, and other contrasting pairs. Countries with genetically similar populations can have divergent outcomes due to cultural and social factors. Within a country, however, most important aspects of culture and society are the same for everyone or are selected by individuals based on their preferences and abilities. In the former case, they obviously can’t explain differences between people in the same country. In the latter case, the cultural and social differences might be an expression of underlying genetic differences.

Before going on, I want to be clear that this is not a question of genetic versus environmental determinism. It is not a question of whether genes or environment cause an attribute, nor a question of how much each contributes to that attribute. Genetic and environmental causes are not mutually exclusive, nor are they independent. Every attribute of an organism has necessary genetic causes and necessary environmental causes. In most cases, those causes do not simply add up to produce the attribute.

Consider your height, for example. It depends on genes that affect growth. It also depends on oxygen, because without oxygen you would have died long ago, and never grown at all. We wouldn’t say that genes caused 50% of your height, oxygen caused 24%, food caused 16%, and so on. Those are necessary causes of your height, and their effects are not additive.

No attribute of an organism is exclusively genetically or environmentally determined. However, differences between individuals and populations can be explained as due to genetic or environmental differences. It would be a fallacy to say that height is 90% genetic. It is not a fallacy to say that a difference in average height between two populations is 90% due to genetic differences.

Suppose that I planted a blueberry seed and a redwood seed on a windswept mountaintop. If they survived, they would both grow into stunted, wind-pruned shrubs of about the same size. Now suppose that I planted a blueberry seed and a redwood seed in a sheltered valley with abundant water and sunshine. The blueberry seed would grow into a bush about 4 feet tall. The redwood seed would grow into a tree more than 100 feet tall.

The difference in height between the two plants depends on both genetic and environmental factors. When the environment is marginal for both plants, their heights do not reflect their genetic potentials. In a good environment, both will attain their full genetic potentials for height. The good environment brings out the genetic differences between them.

Limiting-factor models of growth are common in biology. In a limiting-factor model, the outcome is controlled by the worst factor, which is often the scarcest resource. For example, a crop yield is typically limited by the scarcest resource. If water is scarce, then the crop yield will be limited by the amount of water. If water is abundant, then the crop yield will be limited by something else, such as phosphorus or sunshine. The yield will be limited by the worst factor. If water is the limiting factor, phosphate fertilizer will not increase the yield. If phosphorus is the limiting factor, adding water will not increase the yield. To improve the outcome, you have to act on the limiting factor.

We can model human development in the same way. A trait such as IQ has a genetic potential. It is also limited by environmental factors, such as education and nutrition. If the environmental factors are good, then the limiting factor will be genetic potential. If the limiting factor is genetic, improving education or nutrition will not raise IQ.

When people are malnourished or otherwise materially deprived, their full genetic potential will not be actualized. They will be “stunted”. In a society where some people are malnourished or materially deprived, mental and physical differences could be mostly explained by environmental factors. In such a society, better nutrition, education and medical care could improve outcomes. In the developed world, however, most people have adequate food, shelter, medical care and other aspects of material welfare. Thus, most differences in outcomes are due to differences in genes.

There are exceptions, of course. Having very abusive or neglectful parents can limit a child’s potential. Also, certain extreme outcomes, such as being ultra-rich or famous, are still environmentally determined to a large extent. The child of a billionaire is much more likely to be ultra-rich, mostly due to inheritance. The child of a movie star will have a much easier time getting into movies than a person of equal acting ability with no Hollywood connections. So, extremely bad environments can limit outcomes, and certain extreme outcomes are highly dependent on special environmental conditions. For most people, however, the environment is not the limiting factor that determines outcomes.

For over a century, Western societies have tried to create equality of opportunity. Abundance has enabled this. We have tried to give every child a good environment to grow up in: adequate food, shelter, medical care, protection from violence, and access to education. I think we have been successful in doing this to the greatest extent possible without making outcomes worse. To go further would require drastic measures that would probably make life harder for almost everyone.

In a modern Western society, almost every child has better access to food, medical care, shelter and education than Isaac Newton or Albert Einstein had. But not every child ends up like Isaac Newton or Albert Einstein. There is one privilege of birth that we have not equalized or made unimportant: genetic potential.

Consider the black | white gap in the US, for example. Blacks perform worse on IQ tests. They have lower levels of educational attainment, in spite of affirmative action. They commit more violent crime, per capita, than whites. They are more likely to be murdered (usually by fellow blacks). They have lower average incomes. They use welfare at greater rates. Black children are more likely to live in fatherless households. On many socio-economic measures, blacks perform worse than whites — either worse for themselves or worse for society.

The politically correct explanation for the black | white gap is that it is due to the legacy of slavery, or systemic racism, or poverty, or ghetto culture … or anything else other than genetic differences. There are problems with all of those explanations. Slavery was a long time ago, and it was common all over the world, not just in the US. If systemic racism causes black | white differences, why do Asians outperform whites on most socio-economic metrics? Why hasn’t over 50 years of intensive cultural engineering (“anti-racism” propaganda and education) eliminated racism? Why hasn’t over 50 years of social engineering (school lunches, affirmative action, focusing on minorities) erased the black | white gaps in income, welfare-use, single-parenthood and IQ? How does “racism” or “poverty” (in the modern sense) explain either ghetto culture or the black-on-black murder rate?

Politically correct explanations also violate the principle of parsimony, known as “Occam’s razor”. We know that blacks and whites are genetically different, because racial categories are based on traits that are known to be determined by genes, such as skin color, hair type and facial structure. So, a genetic difference is the simplest explanation for any other observed difference between the categories. That should be the default hypothesis, and other explanations should only be considered if there is evidence that cannot be explained by genetic differences.

There is no rational, honest reason to propose cultural or social explanations of the black | white gap. The genetic explanation is sufficient. It is the simplest explanation, and there is no evidence that it does not explain.

There are environmental differences between racial categories in the developed world. It is possible that they play a secondary role in creating the black | white gap. However, those environmental differences are probably mostly due to genetic differences. The environment is affected by genes.

For example, consider the environmental hazard of lead exposure, which can prevent a child from reaching his full genetic IQ potential. Lead exposure is an environmental factor that could limit outcomes, and that might be distributed unequally by race. However, it is also highly dependent on genes.

Lead exposure is a widely recognized hazard. I have known about it since my childhood. I have tried to limit my lead exposure and the lead exposure of my children. Anyone can do that. You run the water before you use it and/or use filters. You avoid housing with lead paint and/or you make sure children aren’t exposed to paint chips and dust. It’s not that expensive or complicated. But you have to be moderately intelligent, so that you can understand the problem, and you have to be concerned about it. More intelligent and anxious people will limit the lead exposure of themselves and their children. Less anxious or less intelligent people won’t. Intelligence and anxiety both depend on genes.

So, if most aspects of the environment depend on the traits of individuals, and almost all of those traits depend on genes, then it doesn’t make sense to label a problem “environmental”, as if genes were irrelevant to it. The problem of lead exposure is not just environmental. It is also genetic.

Single-parenthood is another example. Being a single parent is a choice that parents make, and that choice is not independent of genes. Personal and social responsibility is probably affected by genes. Less responsible parents are less likely to form stable families. They will provide a worse environment for their children to grow up in. They will also pass on the genetic basis of their irresponsibility. Single-parenthood is an environmental factor, but it depends on the genes of the parents, and it is correlated with the genes of the child.

In a twin adoption study, the effect of single-parenthood or lead exposure will not contribute to a heritability estimate. It will contribute to the “environmental/noise” component, even though it would normally be correlated with the child’s genes. The reason is that the causal route is indirect. The effect depends on the parent’s behavior, not the child’s. Adoption decorrelates the indirect effects of parental genes on the child. Twin adoption studies can only measure the direct effects of genes on outcomes.

A child’s environment not only depends on the genes of his parents. It also depends on the genes of the people who live in his neighborhood.

Generally speaking, it is the kids who make a school good or bad. Kids with lower levels of intelligence and anxiety create a classroom environment that is bad for learning. Teachers spend more time dealing with behavioral problems, and they have to teach down to the average level of intelligence in the classroom.

Likewise, it is the people who make the ghetto a bad environment. It is not the streets, the buildings or even the average income. The poverty and crime of the ghetto is an expression of the genes of the people who live there.

After WWII, the Japanese were far more materially deprived than blacks in the modern US. But the Japanese didn’t act like the black population of the US today. They rebuilt their war-shattered country into a prosperous and safe society. If poverty is a vicious cycle, then Tokyo would resemble the ghetto areas of Baltimore or Detroit. But it doesn’t.

Genetic differences are not exclusively racial, of course. Race just makes them easier to see and talk about.

In the modern West, the worst thing about being poor is that you have to live around the kind of people who end up being poor. What makes poverty bad is the people that you have to associate with, not material deprivation. Productive and responsible people spend a lot of money to live among other productive and responsible people. The main reason to seek wealth in the modern West is simply to live around better people.

Your environment depends a lot on your genes and the genes of people around you. To a large extent, people are the environment. And the genes of people around you are not uncorrelated with your genes. Your parent’s genes are obviously correlated with yours. People of the same racial or ethnic community have correlated genes. Productive and responsible people tend to associate with other productive and responsible people. Likewise, unproductive and irresponsible people tend to associate with other unproductive and irresponsible people. People self-organize by genetic differences in various ways. That creates local environments that can amplify genetic differences.

So, although environmental factors play a role in outcomes, those environmental factors are highly dependent on genes.

Can racial outcome gaps be reduced with top-down social interventions? Yes, to some extent. Removing lead paint and plumbing could make some inner-city housing less hazardous. More aggressive policing could probably lower the black crime rate. More aggressive discipline in schools could probably improve black academic achievement. The environment matters. But the differences between racial demographics are not primarily due to environmental differences. They are primarily due to genetic differences. It would require unequal treatment to equalize racial outcomes.

We have succeeded in eliminating most of the large-scale environmental problems that limited individual development in the past. The remaining environmental problems are local, and are mostly due to local genetic variation. We have already done all the large-scale interventions that could improve outcomes. To improve outcomes further (without eugenics) would require small-scale interventions that would be extremely difficult and require totalitarian social control.

Most people in the modern West are not lacking any important environmental input to development. When they are limited by environmental factors, it is mostly because of the traits of people around them. Thus, most differences between racial, sexual and economic demographics in the modern West are due to genetic differences.


  1. You're dismissing Sowell's claims which are pretty compelling.
    He has pretty interesting books, like "Black Rednecks and White Liberals" that you may find surprising. He also claims that leftist policies destroyed the black family and the black neighbourhood (and aspirations for education and work among blacks).

    Leftist policies shouldn't be underestimated. Just a couple of years of communism in any country you look at were enough to completely demotivate industrious people from studying, working hard, picking up trash, or taking care of anything around them. Surely, there was also dysgenic effect because many competent and smart people were killed, but you can spoil and evoke certain "personality" even in animals like dogs and cats depending on the incentives you give them.

    1. Of course social factors matter (and I said that), but they don't explain race differences within the modern West. The leftist policies in the US were not race-specific. They were the same for everyone. Does Sowell have any explanation for why whites and blacks responded differently (on average) to the same incentives? Or why Asians rose above whites economically? Social factors can explain the differences between different societies, such as Venezuela and Colombia, North Korea and South Korea, or even Japan and China, but they don't explain differences between races in the modern West. There has been a huge effort to make people equal in the West over the past 60 or so years, and it hasn't worked, because people aren't biologically equal.
      Communism is a terrible system, but even communism works better with a high IQ population than a low IQ population. The average IQ in Russia is about 100. The average IQ in Venezuela is about 85. That matters. Don't underestimate biology either.

    2. Communism hasn't worked better in Russia by almost any metric that you pick. As a random person, I'd pick Russia over Venezuela only if it's after 1970, and only I had a permit to live in one of the biggest cities (and only if I had no relatives that were somehow branded as "untrustworthy"). Before that, there are decades upon decades of darkness, and around that, there are miles of misery, and I'd take my chances in modern day, criminal and starving Venezuela, thanks. Russians are pretty smart, but intelligence is overrated.

      I'm not underestimating biology. One of my sons is like a little clone of me, not only physically. It's surreal, the way he thinks and the way he approaches problems cannot be explained by the way we raised him or by anything he could have seen or heard. He can't hear my internal monologue, he can't copy my thought process so accurately - and I was doing my best to hide it from him. I'm looking at him as if he's a mirror, and I'm starting to understand that most of my "accomplishments" and "traumas" are actually genetic destiny. This made me look into the family history generations back and my suspicions were confirmed beyond anything I could imagine. My other child is completely different, he's more like his mother and mirrors her family history.

      With that said, I believe you have your own blind spots and we won't move any further on this topic. I don't disagree with your essay. It's valid and important perspective. But it's not the whole truth.


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