The Ongoing Mystery of How DNA Affects Intelligence
We know genes affect intelligence, but we’re years away from understanding how
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It’s the stuff of which sci-fi dystopias are made: Scientists have come up with a blood test for smartness.
Until the past few years, the best science available would have been hard-pressed to reliably identify a snippet of DNA associated with something as complex as human intelligence. Today, thanks to recent advances in behavioral genetics, you can spit into a tube, send it off to a lab, and get a number known as a “polygenic score” that gives your rough odds of having high or low intelligence.
The emerging science of genomics and intelligence has alarmed skeptics outside the small world of behavioral genetics, and for good reason. The history of research into how genes affect intelligence is littered with error, forays into eugenics, and, in some cases, outright atrocity. So it comes as little surprise that present-day science is currently being twisted and weaponized as fodder for racist demagoguery, whether geneticists like it or not.
The newfound ability to look into a person’s genome for markers of intelligence promises — or maybe threatens — to bring about new futures. Some are darkly dystopian: “designer babies” bred for intelligence, children being closed off from educational opportunities in infancy, or the use of genetic markers to justify discrimination. Others are more optimistic: Some believe we could use genetics to develop better personalized education or intervene early to help children with learning disabilities.
What do all these futuristic visions share in common: They’re way ahead of scientific understanding. Intelligence may be written in our genes, but in a language we don’t yet know how to read.
Polygenic scores: Reply hazy, try again
In 2018, geneticist Robert Plomin trained a public spotlight on polygenic scores for intelligence with his book Blueprint: How DNA Makes Us Who We Are. Plomin, one of the early pioneers of the twin and adoption studies that paved the way for current research linking genetics and human behavior, is an unabashed cheerleader for genetic intelligence testing.
