Is being gay linked to genetics? But a major new study, conducted over 20 years, suggests that men who are gay tend to have a greater number of older brothers—and for an actual, scientific reason. What could explain such a phenomenon? The answer may be linked to a specific kind of antibody produced in some mothers who carry male fetuses.
Scientists identify for the first time two specific genes that may foster a predisposition for being gay in men. Anyone choosing sides in the nature vs. But in , a large study by J. One such variation was commonly found in the gene SLITRK6 , which is on chromosome 13 in the region of the brain, the diencephalon, containing the hypothalamus. This is intriguing, since neuroscientist Simon LeVay had discovered in that the hypothalamus of heterosexual men is nearly twice the size it is in homosexual men, and suggested this might be meaningful. Since then, the gene has been found to be active a few days prior to the birth of male mice. So this particular finding is a potential link between the neuroanatomy and molecular genetics of sexual orientation.
That amounts to an evolutionary paradox: gay men have fewer children, so one would expect that the trait would disappear over time. Now a team of researchers has carried out the largest-ever genetic study of sexual orientation and found evidence consistent with one possible explanation. Details of the unpublished study have been described in a public research plan, in two scientific abstracts, and by researchers at a scientific meeting held in June at the Broad Institute, a genome research center in Cambridge, Massachusetts. The hunt for sexual orientation genes—which wades into the polarizing question of whether people are born gay or become so—is part of a boom in genomics research that aims to unveil how genes shape behavior, not just diseases. Powering the new social genetics are huge databases, including the British government—funded UK Biobank and the DNA of millions of customers collected by 23andMe, a consumer gene testing company.
Behavioural genetics has always been ahot bed of controversy. Not because the science of the subject is not up to the mark, but often because of the area of the research it conducts. Earlier this month, things changed a bit.