Hatemi, Peter K6; Medland, Sarah E7; Klemmensen, Robert8; Oskarsson, Sven7; Littvay, Levente7; Dawes, Christopher T7; Verhulst, Brad7; McDermott, Rose7; Nørgaard, Asbjørn Sonne8; Klofstad, Casey A7; Christensen, Kaare9; Johannesson, Magnus7; Magnusson, Patrik K E7; Eaves, Lindon J7; Martin, Nicholas G7
1 Epidemiology, Biostatistics and Biodemography, Department of Public Health, Det Sundhedsvidenskabelige Fakultet, SDU2 The Danish Twin Registry, Department of Public Health, Det Sundhedsvidenskabelige Fakultet, SDU3 Danish Aging Research Center, Department of Public Health, Det Sundhedsvidenskabelige Fakultet, SDU4 Human Genetics, Department of Clinical Research, Det Sundhedsvidenskabelige Fakultet, SDU5 Department of Political Science and Public Management, Faculty of Business and Social Sciences, SDU6 Genetic Epidemiology, Queensland Institute of Medical Research, Brisbane, Australia, firstname.lastname@example.org unknown8 Department of Political Science and Public Management, Faculty of Business and Social Sciences, SDU9 Epidemiology, Biostatistics and Biodemography, Department of Public Health, Det Sundhedsvidenskabelige Fakultet, SDU
Twin analyses of 19 measures of political ideologies from five democracies and genome-wide findings from three populations
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. However, these findings have not been widely accepted or incorporated into the dominant paradigms that explain the etiology of political ideology. This has been attributed in part to measurement and sample limitations, as well the relative absence of molecular genetic studies. Here we present results from original analyses of a combined sample of over 12,000 twins pairs, ascertained from nine different studies conducted in five democracies, sampled over the course of four decades. We provide evidence that genetic factors play a role in the formation of political ideology, regardless of how ideology is measured, the era, or the population sampled. The only exception is a question that explicitly uses the phrase "Left-Right". We then present results from one of the first genome-wide association studies on political ideology using data from three samples: a 1990 Australian sample involving 6,894 individuals from 3,516 families; a 2008 Australian sample of 1,160 related individuals from 635 families and a 2010 Swedish sample involving 3,334 individuals from 2,607 families. No polymorphisms reached genome-wide significance in the meta-analysis. The combined evidence suggests that political ideology constitutes a fundamental aspect of one's genetically informed psychological disposition, but as Fisher proposed long ago, genetic influences on complex traits will be composed of thousands of markers of very small effects and it will require extremely large samples to have enough power in order to identify specific polymorphisms related to complex social traits.
Behavior Genetics, 2014, Vol 44, Issue 3, p. 282-94