Estimates of the genetic contribution to political association range from 0.4 to 0.6.

Judge against the published research as of September 2014. True if twin and family studies published by then (e.g. Alford/Funk/Hibbing 2005, Hatemi et al. and their meta-analyses) mostly give heritability estimates for political ideology or political attitudes of about 0.4 to 0.6, so that the range is a fair summary. Mostly true if the main estimates mostly fall in that band but a few sit a little outside it (e.g. 0.3–0.65), or if the range fits ideology and attitudes but the wording "political association" is a bit loose. Mixed if a substantial share of the main estimates sit well outside the range. Mostly false if the 0.4–0.6 figures exist but are stated as covering political association in general when the main measures of association, such as party identification, have clearly lower heritability estimates (e.g. below about 0.3), so that a narrow finding is stated as general. False if the literature of the time does not support estimates in that range at all.

Set before the research began.

1. E1 Are Political Orientations Genetically Transmitted? | American Political Science Review | Cambridge Core Cambridge University Press (American Political Science Review) · 8 June 2005

   “The results indicate that genetics plays an important role in shaping political attitudes and ideologies but a more modest role in forming party identification;”

2. E2 Genetic and Environmental Transmission of Political Orientations Political Psychology (Wiley/International Society of Political Psychology), authors Funk, Smith, Alford, Hibbing, Eaton, Krueger, Eaves, Hibbing · 2013

   “The univariate heritability analyses showed that each has significant genetic influences and significant environmental influences, with the latter concentrated in unique rather than shared environment.”

3. E3 Genetic and Environmental Transmission of Political Orientations Political Psychology (Funk, Smith, Alford, Hibbing, Eaton, Krueger, Eaves, Hibbing) · 2013

   “The central conclusion stemming from our univariate analyses is that taken individually, all of our measures have significant genetic and (unique) environmental influences.”

4. E4 Genetic and Environmental Transmission of Political Orientations Political Psychology (Funk, Smith, Alford, Hibbing, Eaton, Krueger, Eaves, Hibbing) · 2013

   “These findings are broadly consistent with previous research that has looked at the heritability of personality traits (e.g., Jang, Livesely, & Vernon, 1996), right-wing authoritarianism (McCourt et al., 1999), and the Wilson-Patterson ideology measure (Alford et al., 2005; Bouchard et al., 2003; Martin et al., 1986).”

5. E5 Genetic Influences on Political Ideologies: Twin Analyses of 19 Measures of Political Ideologies from Five Democracies and Genome-Wide Findings from Three Populations Behavior Genetics (Springer), by Hatemi, Medland, Klemmensen, Oskarsson, Littvay, Dawes, Verhulst, McDermott, Nørgaard, Klofstad, Christensen, Johannesson, Magnusson, Eaves, Martin · 26 February 2014

   “Almost 40 years ago, evidence from large studies of adult twins and their relatives suggested that between 30 and 60 % of the variance in social and political attitudes could be explained by genetic influences.”

6. E6 Is There a “Party” in Your Genes? Political Research Quarterly (Western Political Science Association / SAGE) · September 2009

   “the full model indicates only modest genetic influence (.08 and .12 in females and males, respectively),”

7. E7 Is There a “Party” in Your Genes? Political Research Quarterly (Western Political Science Association / SAGE) · September 2009

   “reported PID was weakly heritable but did not examine the nature of the relationship between political affiliation and important covariates”

8. E8 Are Political Orientations Genetically Transmitted? American Political Science Review (indexed on SciSpace), by John R. Alford, Carolyn Funk, John Hibbing · May 2005

   “to test the hypothesis that, contrary to the assumptions embedded in political science research, political attitudes have genetic as well as environmental causes.”

A 2014 Behavior Genetics review by Hatemi et al. (E5) summarises large twin and family studies as attributing 30–60% of the variance in social and political attitudes to genetic influences. That broadly matches the claimed 0.4–0.6, though the lower bound reaches a little below the claim. Alford/Funk/Hibbing 2005 (E1) and Funk et al. 2013 (E2–E4) likewise find significant genetic influence on political attitudes and ideology. However, E1 and E6–E7 show that party identification is only modestly heritable (about 0.08–0.12 in E6), so the range fits ideology and attitudes, and the broader wording "political association" is loose rather than accurate for every measure.