A study of hundreds of brothers has added to evidence that there is a genetic component in determining who men are sexually attracted to, but makes clear that there is more to it than a “gay gene”
As with so many aspects of human behavior, sexuality has long been subject to a “nature versus nurture” debate, but the idea that people who are attracted to the same-sex are born this way has resonated with LGBT activists and allies. When framed this way, discriminating against them for something beyond their control is similar to discriminating against someone for their gender or the color of their skin. While this makes logical sense, its validity has been occasionally challenged.
The science has been hotly debated as well. In 1993, a Science paper sparked headlines worldwide that talked of a “gay gene”, which was greatly misrepresenting the paper. Speculating on how a gene for same-sex attraction in men might flourish filled newspaper columns.
However, the simplistic notion that a single gene could determine something as complex as sexuality became less and less credible as evidence emerged that so many things previously classified as purely genetic or environmental represent a mix of both. The public discussion, and arguably the scientific research, is heavily influenced by social attitudes. The absence of any quest to find a “straight gene” being one notable example, along with the treatment of sexuality as binary rather than fluid or a spectrum.
Many researchers have turned to twin studies, attempting to see if identical twins are more likely to share a common sexual attraction than those with common upbringing, but different genes. However, these have produced highly divergent results, leaving the question as confused as before.
Dr. Alan Sanders of the NorthShore University HealthSystem Research Institute has been taking a different approach. He has been seeking brothers who both identify as gay, and testing to see what genes they have in common. The research is ongoing, and those interested in participating can contact Sanders. His latest findings have been published in Psychological Medicine.
Sanders looked at the genes of 908 individuals from 409 sets of brothers. Overall these brothers would share half their genomes with each other, but two regions were particularly likely to be similar, suggesting that genes located there might be associated with their sexual orientation. One of these was on the X chromosome, in the same section identified in the Science paper.
The other region, on chromosome 8, has only recently come to attention of researchers in the field.
Even with the largest study yet conducted along these lines, other researchers have questioned whether Sanders' sample size is large enough to deem the results conclusive. Even if eventually accepted, the evidence still leaves plenty of room for other factors, be it other genes, epigenetic effects in the womb or life experiences. Genes for female sexuality have been much less studied, but some research indicates that the alleles that correlate with male same sex attraction are associated with women that have more children.
H/T Huffington Post
