Extraversion Probably Does Not Cause Political Participation. Evidence from Two Genetically Informed Designs

A substantial literature in political psychology has emphasized the importance of personality traits for understanding differences in political participation. One such trait is extraversion. However, the causal status of this relationship is complicated by a number of issues, not least genetic confounding stemming from the heritability of both personality traits and political participation. This study confirms the well-established naive relationship between extraversion and participation, but goes on with (a) a discordant MZ twin design and (b) a new approach using measured genetic variation, or a polygenic index, in the given trait (extraversion) to assess the causal nature of this relationship. First, utilizing variation in extraversion and participation within identical twin pairs shows that twins with higher extraversion do not participate more. Second, random variation within fraternal twin pairs in a polygenic index of extraversion does predict trait extraversion, but does not predict political participation. In summary, previously identified associations between extraversion and political participation are not likely to be causal, but instead reflect common underlying familial factors.