Twin Research and Human Genetics

Table of Contents - February 2012 - Volume 15, Issue 01 (Special Section: The Intersection of Behavioral Genetics and Political Science)  

Special Section: The Intersection of Behavioral Genetics and Political Science

Do Heritability Estimates of Political Phenotypes Suffer From an Equal Environment Assumption Violation? Evidence From an Empirical Study

Levente Littvaya1a2 c1

a1 Department of Political Science, Central European University, Budapest, Hungary

a2 Visiting Scholar, Department of Political Science, Washington State University

Abstract

Using data from the Minnesota Twins Political Survey, this paper tests for the presence of unequal environments (EEA) by zygosity in political attitudes. Equal environment measures used include shared bedroom, friends, classes, and dressing alike. Results show an EEA violation at p < .05 in 5% of the models tested. The violations' impact on heritability estimates and their confidence levels appear random in magnitude and direction. No reasonable post hoc explanation emerged for understanding the presence of the violation in some items but not others. This article establishes reasonable priors for the absence of EEA violations in political phenotypes based on the tested environmental components. The findings place the burden on critics to present theoretical work on the specific mechanisms of EEA violations based on which additional empirical assessments could (and should) be conducted.

(Received October 17 2011)

(Accepted December 01 2011)

Keywords

  • equal environment assumption;
  • ideology;
  • Wilson-Patterson;
  • Minnesota Twins Political Survey

Correspondence:

c1 Address for Correspondence: Levente Littvay, Central European University, Department of Political Science, Nador u. 9, Budapest 1051 Hungary. Email: littvayl@ceu-budapest.edu

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