Genes and politics

Usually that's a title about something related to cloning or stem cells or something. But in this case, it's about the fact that your vote may be heritable! I'm posting this because I just lectured about heritability last week. Like usual, I noted that political affiliation exhibits strong familial effects, but that these are mostly due to shared environment and not genetic variance.

Little did I know that a new study would show that genes do play a substantial role. In a twin study that numbered over 8,000 sets of twins, researchers asked questions about political hot-button topics and general political preferences.

On school prayer, for example, the identical twins' opinions correlated at a rate of 0.66, a measure of how often they agreed. The correlation rate for fraternal twins was 0.46. This translated into a 41 percent contribution from inheritance.
As found in previous studies, attitudes about issues like school prayer, property taxes and the draft were among the most influenced by inheritance, the researchers found. Others like modern art and divorce were less so. And in the twins' overall score, derived from 28 questions, genes accounted for 53 percent of the differences.
But after correcting for the tendency of politically like-minded men and women to marry each other, the researchers also found that the twins' self-identification as Republican or Democrat was far more dependent on environmental factors like upbringing and life experience than was their social orientation, which the researchers call ideology. Inheritance accounted for 14 percent of the difference in party, the researchers found.

And then there's this:

A mismatch between an inherited social orientation and a given party may also explain why some people defect from a party. Many people who are genetically conservative may be brought up as Democrats, and some who are genetically more progressive may be raised as Republicans, the researchers say.

So political party membership may not be strongly heritable, but the tendency to defect, given a conflict with the parental party, may be.

Much more good stuff in the article, including the speculation that the country may become increasingly polarized.