On a fallacious argument about ethnicity and genetics

Here’s a set of beliefs that seem to be widely held among researchers in genetics, and others.

1.     Many groups in society are genetically different from each other. The shy have genetic differences from the sociable, the fat from the thin, the tall from the short, and even the rich from the poor.

2.     However, ethnic groups are not defined by genetics in this way.

(a)   Ethnicity is not a primordial genetic essence. Instead, ethnic groups are socially constructed.

(b)  As a result, there are no important genetic differences between ethnic groups.

For example, The American Society of Human Genetics in its statement on “Attempts to Link Genetics and Racial Supremacy” says:

Although a person’s genetics influences their phenotypic characteristics, and self-identified race might be influenced by physical appearance, race itself is a social construct. Any attempt to use genetics to rank populations demonstrates a fundamental misunderstanding of genetics.

Here’s Eric Turkheimer making a similar, but subtler, point:

Isn't it a contradiction to say that racial differences in intelligence are environmental, but social class differences significantly genetic? No, and the difference is precisely that social class is fluid, whereas race, in any frame shorter than evolutionary time, is fixed by its social construction. Siblings do not sort themselves into different races on the basis of their intelligence, but that is exactly what they do for social class.

And here’s Ta-Nehisi Coates in the Atlantic:

When the liberal says “race is a social construct,” he is not being a soft-headed dolt; he is speaking a historical truth…. It is no more legitimate to ask “Is the black race dumber than then white race?” than it is to ask “Is the Jewish race thriftier than the Arab race?”… The strongest argument for “race” is that people who trace their ancestry back to Europe, and people who trace most of their ancestry back to sub-Saharan Africa, and people who trace most of their ancestry back to Asia, and people who trace their ancestry back to the early Americas, lived isolated from each other for long periods and have evolved different physical traits… But this theoretical definition (already fuzzy) wilts under human agency, in a real world where Kevin Garnett, Harold Ford, and Halle Berry all check “black” on the census…. The reasons for that take us right back to the fact of race as a social construct.

My view is that 1 is true, and 2a is true; but 2b does not follow from 2a. In fact, 2a is more likely to make 2b false than true.

But first, let’s go over the evidence for points 1 and 2a.

Point 1: genetic differences

Geneticists believe point 1 because they think that many differences between humans are caused by genetics. They believe this because of twin studies, which compare identical to non-identical twins. Most twin studies find that identical twins are more similar than non-identical twins on their outcome measure. This holds for many physical characteristics, like height and body mass index; and, as it turns out, for many behavioural characteristics like how much TV you watch or whether you get divorced.

In other words, twin studies show that more genetically similar people (identical twins) are more similar on their outcome. Or to flip it round, similar people on the outcome measure are genetically similar too. This was a surprising discovery, but it has now been confirmed many times, so much that Eric Turkheimer’s first law of behavioural genetics is “all human traits are heritable”.

Today, we can actually describe some of the genetics associated with many characteristics, for example because we’ve created polygenic scores to predict them.

Point 1 just rephrases this idea. You can group people by any characteristic: the rich and the poor, the single and the married, and so on. Well, on average, people in these groups have different genes.

Point 2a: what is ethnicity?

In the nineteenth century, people thought of ethnicity or nationality or race as something natural. After Darwin, they may even have believed that ethnic groups evolved to be different. Intuitively, people still talk as if someone’s ethnicity is an immutable fact about them.

Most modern social scientists don’t think that way. They see ethnicity as a social construct. Someone’s ethnicity is a fact, yes, but it’s a fact like the value of a ten pound note, not like the molecular mass of gold.

Gold has mass whatever people think, but a ten pound note is valuable because people think it is. You discover its value not by analysing the paper chemically, but by asking others what they will pay for it — perhaps you look it up on the foreign exchange market, or find out how many hamburgers it will buy.

Ethnicity is like that. You may think of yourself as a Tamil, but if you come to the US people might just see you as “Asian”, lumping you in with the five billion other people in Asia. Ethnic identity is a name others give you, or a name you give yourself. Many people have tried to “pass” as a different ethnicity, but ultimately, your view only counts if others accept it. Just ask an Ephraimite trying to pronounce the word “shibboleth”:

And the Gileadites took the passages of Jordan before the Ephraimites: and it was so, that when those Ephraimites which were escaped said, Let me go over; that the men of Gilead said unto him, Art thou an Ephraimite? If he said, Nay;

Then said they unto him, Say now Shibboleth: and he said Sibboleth: for he could not frame to pronounce it right. Then they took him, and slew him at the passages of Jordan: and there fell at that time of the Ephraimites forty and two thousand.

Judges 12.5-6

Ethnicity isn’t just social, it’s political. The US Census used to ask people if they were white or black. In 1980 they added a separate question: “are you Hispanic”? In 2020 they merged the questions, with a single question which has checkboxes for white, black and Hispanic and which asks respondents to check all that apply. Obviously, what changed was not people’s genetics, but the emergence of Hispanic as a separate ethnic identity alongside white and black. Immigrants to the US from Latin America started to feel they had common interests. So they started calling themselves “hispanics”, and other people did the same thing.

In African democracies, people’s sense of ethnic identity gets stronger around election time, as politicians use it to rally support. This even affects how people treat each other in the street: in Ghana, taxi drivers charge higher fares to “opposed” ethnic groups around election time. In Kenya, people identify strongly with their tribe; in Tanzania across the border, identification with the same tribes is much weaker. This is probably because of politics. Tanzania’s leader after independence, Julius Nyerere, was a nation-builder who wanted to submerge tribes in an overarching identity, whereas Kenyan politicians used ethnic groups as a power base.

Obviously, people tend to get their ethnic identity from their parents, and this will often correlate with genetic facts like people’s physical appearance. But fundamentally, ethnicity isn’t genetic. It’s more like supporting the same sports team as your parents. Ethnic groups are teams. That doesn’t mean they’re not real. They’re very real, but it’s a social reality, constructed out of belonging and collective action, not a natural one made out of DNA.

Genetics of a social construct

Point 2a is true. But does it imply 2b?

The genetic differences of the groups in part 1 are not age-old ancestral differences. Fat and thin people differ genetically, on average, because some genes make you fat. The same for shy and sociable, rich and poor.

If ethnicity is a socially ascribed category, why shouldn’t it be like that too?

Let me suggest a concrete example. It’s well known that in the UK, white children are less likely than any other ethnic group to enter higher education, and this has been true for at least 15 years. White working-class kids are particularly disadvantaged.

What could explain this? Surely there are many reasons, from culture to geography. I submit that genetic differences are one perfectly plausible explanation.

To be clear, I say that is a plausible explanation, not the true one. I have no evidence for it. But I also see nothing that rules it out, and at least one argument that favours it. (And, obviously, I don’t believe that it is very wicked of me even to raise the possibility — more on this in future.) It could be true.

Why would I think that? Have I been reading too much Oswald Spengler?

It’s simpler than that. You see, many ethnic minority children have what the Germans call a Migrationshintergrund – one or more of their parents, grandparents, or an earlier generation came to the UK from elsewhere in the world. And people coming to the UK from elsewhere in the world are selected in several ways.

The UK’s points system for getting a visa

• Most obviously, it helps in getting a visa if you are educated. Under the new points-based system, you need 70 points to apply to work in the UK. Speaking English well enough gets you 20 points; having a PhD gets you 10-20 more. It also helps if you are coming to a well-paid job. The visa system has explicitly favoured education since at least 2002.

• Even absent these explicit hoops to jump through, migrants are not randomly chosen from their countries of origin. Migration takes resources, so migrants may need to be richer than average. And moving thousands of miles to a foreign country probably requires force of character, as well as the belief that you can make it pay.

All these factors favour people with skills and human capital. Since these are partly genetically controlled, they will be passed down from parent to child. “White British” people, by contrast, don’t need to jump through any hoops to live in the UK. They just had to be born here.

In short, when you compare whites with non-whites in Britain (or many other European countries) you are comparing an unselected group with a highly selected sample. Is it really surprising that parents who had the courage and flexibility to make it halfway round the world might be different from those who didn’t?

These are reasons why white and non-white UK students might have different levels of genetic variants predicting education. They are nothing to do with ancestral differences or long-run evolution. This is a story of sample selection, not natural selection. And again, I emphasize that this is just a hypothesis to illustrate my point — maybe it’s true, maybe not, that’s an empirical question.

One possible response is “but these differences would tell us nothing about white and non-white populations as a whole. They only tell us about the select groups of people who migrated to one particular country.” If you think that, then let me remind you that ethnicity is not a primordial genetic essence, and that ethnic groups are socially constructed! The real ethnic groups in the UK are white people in the UK, South Asians in the UK and so on. These are the groups whose life chances are measured by statistics agencies and sometimes make headlines, who march on demonstrations and whose votes politicians court. They are what we actually care about. As indicators of genetic ancestry, transnational “races” might be helpful.¹ As contemporary ethnic groups, they are basically imaginary. (The exceptions prove the rule. American Jews, Irish Americans, Cuban Americans, Turks in Germany and others are often deeply interested in their “homelands”. But these are nationalities, not just ethnicities, and their forms of transnational solidarity are tied to the politics of their respective states.)

When you stop thinking about ethnicity as being primordial, it becomes just like any other characteristic. But that might make it more, not less, likely to correlate with genetic differences that matter.

I don’t claim there are no ancestral differences between ethnic groups. We know there are from famous pictures like the one below, which plot the principal components of people’s DNA on to maps of where they came from.

From “Genes mirror geography within Europe”, Nature 2008

But these may not be genetic differences that matter. Much of what you see here is just random drift which has no important consequences for outcomes. It’s an open question whether there is also evolution for any given characteristic.

Saying all this opens up two broad questions. First of all, what does it mean to say that (some of) an intergroup difference is caused by genetics? How could we even find out? Second, if we could, should we? Is research on this topic fundamentally harmful, like research on new chemical weapons? I’ll address these in a future post.

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1. Though even in terms of ancestry, African Americans (e.g.) are not descended from a random subset of Africans.