Sunday, February 20, 2005


There's a VERY interesting interview with an expert in population biology, Gregory Cochran, here on the subject of the so-called "gay gene" -- a gene nobody has been able to find. I didn't realize that the rate of discordance among indentical twins was so high. Identical twins are normally identical in just about EVERYTHING so the fact that only one of a pair of identical twins tends to be homosexual is most telling. It is just about as good a proof of NON-genetic causation as you can get. The idea that homosexuality is caused by such environmental influences as poor social skills or a female-dominated home would seem to be ruled out by the twin studies too as identical twins also tend to have a very similar environment as well as identical genes. There is another article by Cochran here setting out his thinking on the matter. Basically, he says that if genes and upbringing don't make you homosexual, viruses probably do. You can actually "catch" homosexuality. If ever his theories become widely known, I think his life will be in danger. At the least there would be attempts to lock him up for "hate speech".

I think, however, that he overlooks an important third possibility -- inadequate nutrition in utero. And, strangely, that could also explain the discordant findings among monozygotic twins -- via intra-uterine competition. Intra-uterine competition? Sometimes identical twins will come out looking very different because some accident of placenta placement has caused one twin to get a far better supply of blood and its nutrients than the other twin got. And if homosexuality is caused by an abnormality of fetal brain development -- as has often been suggested -- poor fetal nutrition generally (including that caused by intra-uterine competition) could be the cause of it. So I wouldn't start dodging all contact with homosexuals yet.

I disagree partly with Cochran's explanation for Jewish intelligence too. He seems to think that the Askenazim have been heavily endogamous. Endogamy is certainly their law but it is much belied by appearances. Many Askenazis are of a distinctly Mediterranean appearance but there are also lots who are distinctly Nordic in appearance. I have known several Jews of Lithuanian origin and they look an awful lot like other Lithuanians (very fair) to me. So I think one of Cochran's basic assumptions is almost certainly wrong -- though I can think of several ways out of the problem -- saying that the exogamy predated the selective pressures on IQ, for instance.


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