The various events and experiences that occur during the course of people's lifetimes are widely assumed to be the source of their political beliefs and behaviors, yet research from behavioral genetics, using the classic twin design, consistently finds that another important source is biology; specifically, it finds that people inherit political predispositions. These predispositions do not equate to genetic determinism, but the fact that even a portion of the variation in political orientations springs from genetics is surprising.
To date, the data employed to draw conclusions regarding the heritability of political orientations have been limited. Scholars whose primary concerns are physical conditions and mental health occasionally ask brief batteries of questions about political beliefs, but the details and intensities of these beliefs have never been assessed by geneticists. Moreover, the heritability of political behaviors (do people vote, work in campaigns, contribute money, join interest groups, contact officials, follow politics, or try to persuade others?) has not been ascertained.
This project compiles the first complete data set on the political orientations and behaviors of twins in the United States. As such, it makes possible the first estimates of the heritability of not just political beliefs but also the intensity of those beliefs and the political behaviors generated by those beliefs.
One notable broader impact of this project is that, upon dissemination, this comprehensive data set will be the first to allow mainstream political scientists to conduct their own analyses of the environmental and genetic contributions to politics. Existing data sets collected by behavioral geneticists are both proprietary and contain limited political content. The data collected in conjunction with this project allow social scientists to integrate their empirical work with that in the life sciences, thus helping to encourage a long-overdue melding of the social and biological sciences and a more complete accounting of the nature of the human condition and more specifically of the sources of mass-scale politics.
