VOTING: IN YOUR GENES?
August 8, 2008
Numerous studies over the past two decades have indicated that genes have a significant influence over whether you're "liberal" or "conservative" on various political and social issues. Some heritability estimates have been as high as 50 percent. That's roughly the heritability found for many personality traits such as "extraversion" or "agreeableness," and it implies that, in a given population, about half of the variation in a particular trait is attributable to genetic differences, says Science magazine.
Now James Fowler, a political scientist at the University of California, San Diego, and grad student Christopher Dawes say they've produced fresh evidence that DNA also has a hand in the intensity of someone's partisan attachment and even in whether someone bothers to vote.
They did that by crunching data from twin registries and the government's long-running National Longitudinal Study of Adolescent Health (NLSAH):
- In one study, the researchers matched data on voting by 396 Los Angeles-area twins, including identical (who share 100 percent of their genes) and fraternal (who average 50 percent genetic overlap) twins, obtained from Los Angeles voter-turnout records.
- All twins were same-sex pairs to avoid confounding results with sex differences.
- The researchers corrected for environmental factors such as whether more of the identical than fraternal twins were living together, which might inflate their degree of similarity.
The researchers concluded:
- The correlation for voting was much higher between pairs of identical (.71) than fraternal (.50) twins.
- From this they estimated the heritability of voting behavior--that is, whether people eligible to vote actually do so -- at 53 percent, suggesting that at least half the individual variation can be traced to genetic influences.
- They found an even higher heritability -- 72 percent -- when they replicated the study with data on 806 twins from NLSAH, they reported in the May issue of the American Political Science Review.
Source: Constance Holden, "Voting: In Your Genes?" Science, Vol. 321, No. 5888, July 25, 2008.
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