Razib over at Gene Expression has a post on the heritability of voting intentions. The actual paper he cites is unreadable even by social science standards, but if you click on where Razib says “I’ve blogged it elsewhere,” there’s some more accessible stuff.
Once again — it seems to be a Golden Rule of all these studies into heritability of behavior and personality traits (or perhaps just of the ones that draw from twin studies) — genetic effects account for around 50 percent of the variance. In this zone, half of everything is genetic.
[That’s 6,950. This is more fun than watching your car’s odometer cycle round!]