A massive new study lays out the map of our genetic intelligence

Both nature and nurture affect intelligence.
Both nature and nurture affect intelligence.
Image: Reuters
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Your intelligence is partly due to hard work, nutrition, and education. But you can also thank (or blame) your genes for your mental abilities.

Decades of work on twin studies suggest that genes account for roughly half of variations in IQ seen across a population. And a meta-analysis published this week in Nature on nearly 80,000 people has identified 40 specific genes that affect intelligence. The one study more than quadrupled the number of genes scientists know of that shape intelligence, bringing the total number to 52.

There’s still a long way to go. The currently known genes are thought to account for just 4.8% of variations in IQ, meaning that there are hundreds of genes that play a role in intelligence and are yet to be discovered.

But plenty of people are anxious about scientists heading down that path, and what will happen when they reach the end of it. Perfectly understanding the genetics behind intelligence could guide practices like designer babies and IQ-based eugenics, raising major ethical questions. It also presents an uncompromising but disquieting truth: That some people will just never be as intelligent as others, simply because of their genetics.

I’ve written before about how the science of behavioral genetics makes many people uncomfortable, and several researchers told me they’ve met people who refuse to accept that genes do have a powerful effect on educational success.

But these genetic scientists insist that concerns about their field are misplaced, and that their research has many potential benefits. In an editorial also published in Nature shortly following the meta-analysis, the authors of the study acknowledge the controversy—“Why are psychology undergraduates denied tuition in what is surely one of the most central and influential human traits?” they write—and say many concerns derive from racist eugenic practices of the past. But the genetics of intelligence is “complex and subtle,” as Nature’s editorial says, and simply doesn’t support prejudiced theories of racial superiority. In fact, they argue, better understanding the genetics underlying intelligence will disprove racist theories of eugenicists.

Meanwhile concerns of biological determinism—that understanding the genetics of intelligence could lead to a world where some people are given more education or opportunities than others based on their innate abilities—are unfounded, as genes certainly aren’t the only factor that influences intelligence. Education, nutrition, and other childhood circumstances are just as crucial to variations in IQ. In other words, nurture has just as much of an effect as nature, and education and lifestyle will never stop being massively important.

And though designer babies are a dystopian possibility, they’re a long way off. “You certainly wouldn’t be able to design a baby based on the current knowledge,” Danielle Posthuma, statistical geneticist at the Free University of Amsterdam and lead author of the meta-analysis study, told the Guardian.

There are potentially nefarious uses for all kinds of scientific advances, but this shouldn’t prevent researchers from furthering scientific knowledge. Understanding the genetics behind intelligence could lead to personalized educational techniques depending on someone’s genes, or potentially be used to treat cognitive impairments in old age. And, ultimately, unraveling what actually makes us intelligent would be far more useful than the existing myths and misinformation around the subject.

For now, we know that intelligence is partly hereditary, meaning that you can thank your parents for the way you think. But they’re not the only ones who deserve credit.