How to test gay gene theory

http://www.iSteve.com/05JanA.htm#clone.gay.sheep

Let's clone a gay sheep! Greg Cochran's come up with a way to test the popular but almost untested Gay Gene theory: clone a homosexual ram. Although you hear a lot about homosexuality in animals, most of that is actually bisexuality. There is very little in the way of exclusive homosexual orientation among male animals -- but sheep are a clear exception, much to the frustration of sheep ranchers who find that a noticeable percentage of their rams won't pay attention to a ewe in heat even if you tie her to a fence for his convenience.

Since we've known how to clone sheep since the 1990s, it would be straightforward to clone a number of exclusively gay rams and see how many of their clones turn out to be gay as well. The gay gene theory would predict that all of them would be gay since their genes would be the same.

By the way, among human identical twins, a substantial portion of the time when one identical twin is homosexual, the other is not. The first time this was studied, just under half of the pairs were "nonconcordant" for homosexuality. However, it was pointed out that by placing an ad in a gay newspaper, this would be more likely to attract concordant twins (since readership of gay newspapers among nonconcordant twins is about half compared to concordant twins; and other readers of the gay newspaper would be more likely to know that, say, Ike had a twin if his twin Mike was also active on the local gay scene than if Mike lived in Schaumburg with his wife and three kids, so they'd be more likely to call the ad to one of the twin's attention if both were gay.)

So, the study was redone using the Australian government's twin registry and they came up with a nonconcordance figure of, I recall, something like 75%-80%. However, there are methodological issues involving that study, too, so we can't be too sure. Nonetheless, it's clear that concordance for male homosexuality among identical twins is much lower than for, say, sex, where it's virtually 100%, or for, say, height where the concordance is quite high.

Let me also throw out a quick way to test a different theory of the origins of homosexuality. It turns out that schizophrenics tend to have birthdates falling more in some seasons of the year than in other seasons, suggesting that prenatal or postnatal infections, which are spread more in winter than in summer, might play a role in schizophrenia. So, are male (or female) homosexuals more likely to be born at some point of the year than at other points of the year? One way to test this is by looking at a gay dating service that displays the participants' astrological signs (i.e., birth months). There ought to be an equal number for each sign, but if there is a statistically significant skew toward one or two seasons, that might suggest some role for infections.

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