Saturday, June 7, 2014

That 'gay' gene may actually be a collection of man-loving/woman-loving genes. There's a difference

About Dean Hamer (from Wayne Bensen): Dr. Dean Hamer was an independent researcher at the National Institutes of Health for 35 years, where he directed the Gene Structure and Regulation Section at the U.S. National Cancer Institute. In 1993, he published a landmark paper showing that the Xq28 marker on the X chromosome was linked to homosexuality. Dr. Hamer received his Ph.D. from Harvard Medical School.

      ...Perhaps “male-loving” alleles (allele: one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome) in a female predispose her to mate earlier and have more children. If their sisters, mother and aunts have more kids who share some of their genes, it would make up for the fewer children of gay males.
     And they do. Lots more children. An Italian group showed that the female relatives of gay men have 1.3 times as many children as the female relatives of straight men. This is a huge selective advantage that a male-loving allele confers on women, and offsets the selective disadvantage that it confers on men.
     I am surprised that this work is not better known, and its explanatory power is neglected in the whole debate about the “normality” of homosexual behaviour...
     We have no idea whether these genetic studies identified “gay alleles” of the same or different genes.
     It is interesting that Hamer detected the original “gay gene” on the X, because this chromosome has more than its fair share of genes that affect reproduction, but I would expect that there are genes all over the genome that contribute to mate choice in humans (female-loving as well as male-loving).
     If there are male-loving and female-loving alleles of tens or hundreds of genes battling it out in the population, everyone will inherit a mixture of different variants. Combined with environmental influences, it will be hard to detect individual genes.
     It’s a bit like height, which is influenced by variants in thousands of genes, as well as the environment, and produces a “continuous distribution” of people of different heights. At the two extremes are the very tall and the very short.
Here's Hamer's testimony in favor of marriage equality in Hawaii:

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