I’ve come up with similar findings in a series of studies done in collaboration with the Yale graduate student Nick Stagnaro. We start by giving people a simple test that measures their degree of empathy. Then we tell them some awful stories, about journalists kidnapped in the Middle East, about child abuse in the United States. And then we ask them how best to respond to those responsible for the suffering. In the Middle East case, we give a continuum of political options, from doing nothing to public criticism, all the way to a military ground invasion. For the domestic version, we ask about increased penalties for the abuser, from increasing their bail to making them eligible for the death penalty. Just as with the genetic study, we found that the more empathic people are, the more they want a harsher punishment.

Politicians are comfortable exploiting this dark side of empathy. Donald Trump likes to talk about Kate—he doesn’t use her full name, Kate Steinle, just Kate. She was murdered in San Francisco by an undocumented immigrant, and Trump wants to make her real to his audience, to make vivid his talk of Mexican killers. Similarly, Ann Coulter’s recent book, Adios, America, is rich with detailed descriptions of immigrant crimes, particularly rape and child rape, with chapter titles like “Why Do Hispanic Valedictorians Make the News, But Child Rapists Don’t?” and headings like “Lost a friend to drugs? Thank a Mexican.” Trump and Coulter use these stories to stoke our feelings for innocent victims, to motivate support for policies against the immigrants who are said to prey upon these innocents.

There is a history of this sort of thing. Lynchings in the American South were often sparked by stories of white women who were assaulted by blacks, and anti-Semitic attacks prior to the Holocaust were often motivated by tales of Jews preying on innocent German children. Who isn’t enraged by someone who hurts a child?