Not by twins alone: Using the extended family design to investigate genetic influence on political beliefs

Peter K. Hatemi, John R. Hibbing, Sarah E. Medland, Matthew C. Keller, John R. Alford, Kevin B. Smith, Nicholas G. Martin, Lindon J. Eaves

Research output: Contribution to journalArticle

98 Scopus citations

Abstract

Variance components estimates of political and social attitudes suggest a substantial level of genetic influence, but the results have been challenged because they rely on data from twins only. In this analysis, we include responses from parents and nontwin full siblings of twins, account for measurement error by using a panel design, and estimate genetic and environmental variance by maximum-likelihood structural equation modeling. By doing so, we address the central concerns of critics, including that the twin-only design offers no verification of either the equal environments or random mating assumptions. Moving beyond the twin-only design leads to the conclusion that for most political and social attitudes, genetic influences account for an even greater proportion of individual differences than reported by studies using more limited data and more elementary estimation techniques. These findings make it increasingly difficult to deny that-however indirectly-genetics plays a role in the formation of political and social attitudes.

Original languageEnglish (US)
Pages (from-to)798-814
Number of pages17
JournalAmerican Journal of Political Science
Volume54
Issue number3
DOIs
StatePublished - Jul 2010

ASJC Scopus subject areas

  • Sociology and Political Science
  • Political Science and International Relations

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