Fowler, Baker, and Dawes (2008) recently showed in two independent studies of twins that voter turnout has very high heritability. Here we investigate two specific genes that may contribute to variation in voting behavior. Using data from the National Longitudinal Study of Adolescent Health, we show that individuals with a polymorphism of the MAOA gene are significantly more likely to have voted in the 2004 presidential election. We also find evidence that an association between a polymorphism of the 5HTT gene and voter turnout is moderated by religious attendance. These are the first results ever to link specific genes to political behavior.
Social scientists have shown that basic political attitudes like liberalism and conservatism are likely to be heritable (Alford, Funk, and Hibbing 2005, Hatemi et al. 2007). While the choice of a particular candidate or party does not appear to be heritable, a significant proportion of the variation in the decision to participate in politics can be attributed to genetic factors. Fowler, Baker, and Dawes (2008) recently studied the voting behavior of two populations of twins and showed that heritability accounted for 53% of the variation in validated turnout of those living in Los Angeles county and 72% of the self-reported turnout in a nationally representative sample of young adults. They also showed that heritability accounted for 60% of the variation in a general index of political participation, including contributing to campaigns, running for office, volunteering for political organizations, and attending protests. These results were the first to suggest that humans exhibit inherent variability in their willingness to participate in politics.However, these initial results based on twin studies beg the question ''which genes?'' The natural place to start the search for such genes is among those that have already been shown to account for variation in social behavior. And among these, MAOA and 5HTT are prime candidates. These two genes transcribe neurochemicals that exert a strong influence on the serotonin system in parts of the brain that regulate fear, trust, and social interaction (Bertolino et al. 2005; Eisenberger et al. 2007;Hariri et al. 2002;Hariri et al. 2005;Heinz et al. 2005;Meyer-Lindenberg et al. 2006). MAOA and 5HTT have been studied for more than 20 years, and much is known about the way different versions of their genes regulate transcription, metabolism, and signal transfers between neurons, all of which have an effect on social interactions (Craig 2007). In particular, the less transcriptionally efficient alleles of these genes have been associated with a variety of antisocial behaviors (Rhee and Waldman 2002).In this article, we hypothesize that people with more transcriptionally efficient alleles of the MAOA and 5HTT genes are more likely to vote. An association between a gene and political behavior may also be moderated by environmental factors. This phenomenon is known as a gene-environment (GxE) interaction (Shanahan and Hofer 2005). We therefore...