Where did your political and religious opinions come from? How did you come by them? What made you who you are?
If you're like most people, you're probably inclined to answer this question by citing two main influences: your upbringing and your life experiences. But according to a growing body of science, such an account leaves out a major factor: your genes.
"The basic idea of a heritable component to political beliefs has been around for at least a quarter of a century," says University of Nebraska-Lincoln political scientist John Hibbing, coauthor of the new book Predisposed: Liberals, Conservatives, and the Biology of Political Differences. "It's shown up too many times, in too many different places, with too many samples. So there's something there."
The science dates back at least to 1986. In that year, the prestigious Proceedings of the National Academy of Sciences published a paper using a classic "twin study" design to try to determine the heritability of a variety of political attitudes, such as views on the death penalty. The researchers concluded that genes could explain a substantial percentage of the variation in responses to an oft-used political questionnaire called the Wilson-Patterson conservatism scale.