Yes, There Is a Genetic Component to Intelligence

Photo: Mario Tama/Getty Images

Chances are, when you hear the term intelligence in the same sentence as hereditary, it makes you at least a little bit uncomfortable. There is, after all, a long, dark history of crank researchers making false claims about genetics to prop up bad ideas ranging from segregation to Nazi race science. Often, when people link the two concepts they don’t have good intentions.

The problem is, intelligence does have a meaningful hereditary component, at least when it comes to the tools we have to measure it, like IQ tests — tools that, while not perfect, correlate with important real-world outcomes like college GPA. That doesn’t mean there isn’t a lot of other stuff going on as well, ranging from early-childhood nutrition to access to early education, but it means that if you want to really understand human intelligence, you can’t simply leave out heredity. And — this is crucial — a belief in a genetic component of intelligence does not inexorably lead to Bell Curve–style arguments about race and IQ, simply because society’s racial categories — black, white, Latino — do not map as neatly to genetics as most people think.

Lately there’s been what feels like a bit of pushback from researchers and others who want to demystify and de-problematize research into the connection between genetics and intelligence. One example came in the form of a Nature editorial published earlier this week, which lamented the extent to which racists and reactionaries have crowded out an important area of research. “The subject, it seems, is dying out on campus because it has echoes of elitism — and worse, racism — that make students and university officials uncomfortable,” write the authors.

The editorial was written in part as a general response to a solid body of research linking genetics to intelligence, but also to a new meta-analysis just published in Nature Genetics: “The research pools together genome-wide association studies looking at a total of nearly 80,000 children and adults. The studies used different measures of ‘general intelligence’, including IQ scores and number of correct answers given to brief touchscreen puzzles. The meta-analysis identifies 18 genomic regions associated with intelligence, and candidate genes that are highly expressed in the brain. The associations, the study suggests, could explain up to 4.8% of the variance in intelligence across these cohorts.”

That means about 95 percent of the intelligence differences in these samples, at least as measured in this manner, did not come down to the genes the researchers examined, which leaves plenty of room for those concerned with environmental influences. But still: That’s a nice little chunk that can be explained by genetic variation.

But why, exactly, should we care about that chunk? Freddie deBoer, an education researcher and blogger, made the case in April that an understanding of innate differences in academic ability can help us build a fairer and juster world:

[A]s we value intelligence in the way we do, progressive people must be willing to be honest about the existence of inherent differences between individuals in academic traits. When we act as if good schooling and committed teachers can bring any student to the pinnacle of academic achievement, we are creating entirely unfair expectations. Meanwhile, failure to recognize the impact of genetics on academic outcomes leaves us unable to combat an increasingly rigid social hierarchy. I often ask people, what happens after we close the racial achievement gap? What becomes the task then? Precisely because I don’t believe in pseudoscientific racism, I believe that we will eventually close the racial achievement gap, if we are willing to confront socioeconomic inequality directly and with government intervention. But what happens then? We will still have a distribution of academic talent. It will simply be a distribution with proportional numbers of black people, of women, of LGBTQ people … Does it therefore follow that those on the bottom of the talent distribution will deserve poverty, hopelessness, and marginalization? I can’t imagine how that could be perceived as a just outcome. But if progressive people fear getting involved in these discussions out of a vague sense that any link between genetics and academic ability is racist, they will not be able to help shape the future.

Anecdotally, just about everyone agrees that even fairly young kids aren’t blank slates when it comes to academic talent as traditionally measured: Some just have more of it, and no amount of hard work will fully bridge the gap between the highest- and lowest-achieving kids in a given class, even if certain initiatives will raise everyone up a bit. DeBoer’s argument, in part, is that it’s important to understand why that is, and to understand that it’s unfair to expect all kids to be operating at the same academic level. “When we act as if good schooling and committed teachers can bring any student to the pinnacle of academic achievement, we are creating entirely unfair expectations,” he writes.

But deBoer is right that just as it’s important not to slip into naïve blank-slate-ism here, it’s equally important not to fall for overzealous strands of genetic determinism, or the idea that genes are destiny. The Nature authors make that same point: “[S]ome worry about the idea that if certain genes are influential in intelligence, individuals without them cannot be bright and successful,” write the Nature authors. “Yet that is not so — environment is crucial, too. The existence of genes ‘for’ intelligence would not imply that education is wasted on people without those genes. Geneticists burned down that straw man long ago.”

This is a complicated area that doesn’t lend itself to easy or intuitive explanations. But there is a tendency, sometimes, for progressive-minded people to approach science in a backwards way: This idea could lead to bad consequences, so it can’t be right. There’s been a bit of that going on with the folks who ardently, against all available evidence, argue that there isn’t a genetic component to intelligence as we measure it.

The problem is that once you abandon a fair reading of the evidence and decide this subject just can’t be talked about — which really is the stance a fair number of progressives have taken — you’re leaving a pretty good-size gap for bad-faith interpreters of that evidence to sneak in and peddle unjustified views about genetics, race, and IQ. If you’re concerned about social justice, in other words, you should also be concerned about sound science.

Yes, There Is a Genetic Component to Intelligence