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Biology, Ideology, and Epistemology: How Do We Know Political Attitudes Are Inherited and Why Should We Care?


  • Data employed in this project were collected with the financial support of the National Science Foundation in the form of SES-0721378, PI: John R. Hibbing; Co-PIs: John R. Alford, Lindon J. Eaves, Carolyn L. Funk, Peter K. Hatemi, and Kevin B. Smith, and with the cooperation of the Minnesota Twin Registry at the University of Minnesota, Robert Krueger and Matthew McGue, Directors.

Kevin Smith is Professor of Political Science, University of Nebraska–Lincoln, 511 Oldfather Hall, Lincoln, NE 68502 ( John R. Alford is Associate Professor of Political Science, Rice University, 6100 Main MS-550, Houston, TX 77005 ( Peter K. Hatemi is Associate Professor of Political Science and Microbiology, The Pennsylvania State University, 307 Pond Lab, University Park, PA 16802 ( Lindon J. Eaves is Distinguished Professor, Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, PO Box 980126, Richmond, VA 23928 ( Carolyn Funk is Director of the Commonwealth Poll and Associate Professor in the L. Douglas Wilder School of Government and Public Affairs, Virginia Commonwealth University, 919 West Franklin Street, Richmond, VA 23284 ( John R. Hibbing is Foundation Regents University Professor of Political Science, University of Nebraska–Lincoln, 511 Oldfather Hall, Lincoln, NE 68502 (


Evidence that political attitudes and behavior are in part biologically and even genetically instantiated is much discussed in political science of late. Yet the classic twin design, a primary source of evidence on this matter, has been criticized for being biased toward finding genetic influence. In this article, we employ a new data source to test empirically the alternative, exclusively environmental, explanations for ideological similarities between twins. We find little support for these explanations and argue that even if we treat them as wholly correct, they provide reasons for political science to pay more rather than less attention to the biological basis of attitudes and behaviors. Our analysis suggests that the mainstream socialization paradigm for explaining attitudes and behaviors is not necessarily incorrect but is substantively incomplete.