For years, researchers have debated the significance of early childhood versus adult experiences in the formation of a person’s political beliefs, but have primarily dismissed the possible role genetics might play.

A 2005 study published in the American Political Science Review, “Are Political Orientations Genetically Transmitted?” (PDF), uses data from existing social science studies involving more than 10,000 sets of identical and non-identical twins from 1980 to 1994 to determine the correlation between genetics and political orientation. Subjects were scored on the basis of their reactions to 28 short phrases with explicit or implicit social and political biases such as ‘death penalty’, ‘abortion,’ or ‘nudist camps.’ Researchers also considered additional variables such as whether each set of twins shared the same environmental conditions.

Key study findings include:

• “Shared influences (genetic and environmental) account for about half of the variation in these political reactions, with unique individual and environmental factors accounting for the remainder.”
• The influence of heredity on social orientation for identical twins exceeds that of environmental factors for every phrase response; this alignment trumps the correlation scores of non-identical twins and all types of twin pairs raised in different environments.
• The phrases that elicited the highest levels of hereditary-based correlation were “school prayer,” “property tax,” “Moral Majority,” “capitalism” and “astrology.”
• The impact of shared environment exceeded that of hereditability in 4 of the 28 test phrases — “living together,” “gay rights,” “abortion” and “liberals.”
• The political attitudes of twins are not determined by the views of their parents; when researchers controlled for parental views, there was no significant difference in the level to which identical twins would still agree with one another.
• However, while respondents’ attitudes correlated strongly with heredity, their party affiliations correlated more strongly with environmental factors: “Clearly, party identification is, at least for the United States, a different sort of beast than reactions to issue items.”

The authors conclude: “Why do social, more than economic, issues tend to hit people in the gut, even though both constitute ongoing and equally complex societal concerns? In light of the new findings, one distinct possibility is that easy ‘gut’ issues tend to be those that are more hereditable.”

Tags: science, elections

By Margaret Weigel | October 31, 2011