The genetics of voting: an Australian twin study.

Previously we and others have shown evidence for genetic influences on political attitudes and sociodemographic indicators (Martin 1987; Posner et al. 1996; Truett et al. 1992; Eaves et al. 1999). However, the nature of the relationship between political attitudes, social indictors and voting behavior has not been investigated. While heritability estimates for social and political attitudes have been reported in previous research, the heritability for vote choice has not. Furthermore, if vote choice is heritable, it is unclear whether the heritable component can be accounted for through the genetic influence on related social and political traits, or if there exists a unique genetic component specific to voting behavior. In mailed surveys of adult Australian twins, we asked respondents to indicate their usual voting preference as well as attitudes on contemporary individual political items. When vote choice was dichotomized as Labor versus Conservative, twin correlations were r (mz) = 0.81 (1,661 pairs), and r (dz) = 0.69 (1,727 pairs) consistent with modest genetic influence (a (2) = 0.24). However, multivariate genetic analysis showed no unique genetic contribution to voting preference; rather, the genetic influence in vote choice could be explained by shared genetic influences in perceived social class, church attendance and certain key political attitude items.