In recent months, some scientists have spotted distortions of their own academic papers in far-right internet forums. Others have fielded confused queries about claims of white superiority wrapped in the jargon of human genetics. Misconceptions about how genes factor into America’s stark racial disparities have surfaced in the nation’s increasingly heated arguments over school achievement gaps, immigration and policing…

One slide Dr. Novembre has folded into his recent talks depicts a group of white nationalists chugging milk at a 2017 gathering to draw attention to a genetic trait known to be more common in white people than others — the ability to digest lactose as adults. It also shows a social media post from an account called “Enter The Milk Zone” with a map lifted from a scientific journal article on the trait’s evolutionary history.

In most of the world, the article explains, the gene that allows for the digestion of lactose switches off after childhood. But with the arrival of the first cattle herders in Europe some 5,000 years ago, a chance mutation that left it turned on provided enough of a nutritional leg up that nearly all of those who survived eventually carried it. In the post, the link is accompanied by a snippet of hate speech urging individuals of African ancestry to leave America. “If you can’t drink milk,” it says in part, “you have to go back.”