Genetic basis for homophobia

Verweij et al (2008) used the Australian Twins Registry (ATR) to examine whether there might be a genetic component to "negative attitudes toward homosexuals and homosexuality (homophobia)". As many other studies have found, women were less likely to hold homophobic beliefs than men, but in contrast with previous studies, no significant effect of age was found. Additionally, the study concluded that homophobic attitudes were "substantially inherited" and that "social environmental influences are relatively minor." However, the strongest effect size came from events outside the family home: "unique environment."

---

I'm frighteningly certain that I've discussed the tendency for women be less homophobic, yet I can't find any post on the topic in previous DBlogs. Seriously? Did I just forget?

At any rate, I'm baffled by the assertion that social environment is a "relatively minor" contributor. The argument here is that because people marry people with similar beliefs, the genetic effect is higher than straight-up numbers demonstrate. Wait, what? I've heard a lot of weird theories argued with assortative mating, but this is by far the wackiest. Wouldn't it make more sense that social beliefs would be especially reinforced in a household where both parents held the belief?

---

Dan4th copies comments to and from DifferenceBlog.com and Diffblog on LJ.
October is DonorsChoose's Blogger Challenge Month. Check out the projects that DifferenceBlog supports this year!