Scientists Find 'Liberal Gene' | NBC San Diego:
According to scientists at UC San Diego and Harvard University, 'ideology is affected not just by social factors, but also by a dopamine receptor gene called DRD4.' That and how many friends you had during high school.
The study was led by UCSD's James Fowler and focused on 2,000 subjects from the National Longitudinal Study of Adolescent Health. Scientists matched the subjects' genetic information with 'maps' of their social networks. According to researchers, they determined that people 'with a specific variant of the DRD4 gene were more likely to be liberal as adults.' However, the, subjects were only more likely to have leanings to the left if they were also socially active during adolescence.