For more than 150 years, the question of nature versus nurture has been one of the most contentious issues in the human sciences. On the one side are "blank-slaters," who believe we are mainly shaped by our environment. On the other side are "hereditarians," who believe in the primacy of genes. From the start, the fight has been highly politicized and extremely bitter, given that it has implications for how we think about racial disparities, meritocracy,...