Is political ideology derived from a person's social environment or is it a result of genetic predisposition?
It's an interaction of both, according to a recent study on our political leanings that boosts both sides of the nature versus nurture debate.
Scientists at the University of California San Diego and Harvard University determined that people who carry a variant of the DRD4 gene are more likely to be liberals as adults, depending on the number of friendships they had during high school. They published their study in a recent issue of The Journal of Politics.
Data was analyzed from the National Longitudinal Study of Adolescent Health (the same source for a recent study that found intelligent children drink more alcohol as adults).
The four authors, including UCSD's James Fowler, wanted to explore if politics were heritable by identifying a specific gene variant associated with political leaning. They hypothesized that individuals with a genetic predisposition toward seeking out new experiences would tend to be more liberal.
The 7R variant of DRD4, a dopamine receptor gene, had previously been associated with novelty seeking. The researchers theorized novelty seeking would be related to openness, a psychological trait that has been associated with political liberalism.
However, social environment was critical. The more friends gene carriers have in high school, the more likely they are to be liberals as adults. The authors write, "Ten friends can move a person with two copies of 7R allele almost halfway from being a conservative to moderate or from being moderate to liberal."
They theorize a larger social network may bring more diverse viewpoints, which could be an influence on the liberal development.
Neither the gene nor social networks alone influenced political identification.
Participants without the gene had no relationship between number of friends and ideology.
The sample consisted of over 2,500 individuals. Respondents were asked during their high school years to name five female and five male friends. The number of nonfamilial friends named was the measure of their social network.
Respondents were later asked in their early 20s to identify themselves as "very conservative," "conservative," "middle-of-the-road," "liberal," or "very liberal."
Prior studies on twins had found that about a third of variation in political attitudes could be attributed to genes and approximately half of the variation explained by environment.
This study purports to be the first to identify a specific gene associated with politics.