ARTICLES

Genetic and Environmental Transmission of Political Attitudes Over a Life Time

Peter K. Hatemi^a1*, Carolyn L. Funk^a2, Sarah E. Medland^a3, Hermine M. Maes^a4, Judy L. Silberg^a5, Nicholas G. Martin^a6 and Lindon J. Eaves^a7*

^a1 University of Iowa

^a2 Virginia Commonwealth University

^a3 Queensland Institute of Medical Research

^a4 Virginia Commonwealth University

^a5 Virginia Commonwealth University

^a6 Queensland Institute of Medical Research

^a7 Virginia Commonwealth University

Abstract

Recently political scientists have looked anew at the source of political preferences and find support for the heuristic that political attitudes and behaviors are influenced by endogenous factors. The present research attempts to characterize how the transmission of political orientations develops over the life course. Using longitudinal data collected on twins throughout childhood and adolescence combined with cross-sectional data from adult twins, the present study finds that genetic influences on political attitudes are absent prior to young adulthood. During childhood and adolescence, individual differences in political attitudes are accounted for by a variety of environmental influences with the role of shared “family” environment, including parental socialization, accumulating markedly between the ages of 9 and 17. However, at the point of early adulthood (in the early 20s), for those who left their parental home, there is evidence of a sizeable genetic influence on political attitudes which remains stable throughout adult life. The pattern of genetic transmission shows some similarity to an “impressionable years” model of attitude crystallization showing both the important influence of family and other shared environmental influences in adolescence and then an increased role of genetic factors as familial environmental influences diminish.

(Received April 08 2008)

(Accepted November 22 2008)

Footnotes

* These authors contributed equally to this work.

Peter K. Hatemi is assistant professor of political science, University of Iowa, Iowa City, IA 52242.

Carolyn L. Funk is associate professor of government and public affairs, Virginia Commonwealth University, Richmond, VA 23284.

Sarah E. Medland is research officer of Genetic Epidemiology, Queensland Institute of Medical Research, QLD 4029, Australia.

Hermine M. Maes is associate professor of Human Genetics and Psychiatry, Virginia Commonwealth University, Richmond, VA 23284.

Judy L. Silberg is associate professor of Human Genetics, Virginia Commonwealth University, Richmond, VA 23284.

Nicholas G. Martin is senior principal research fellow, Queensland Institute of Medical Research, QLD 4029, Australia.

Lindon J. Eaves is distinguished professor of Human Genetics and Psychiatry, Virginia Commonwealth University, Richmond, VA 23284.