A team of US researchers conducted a genome-wide association study that uncovered SNPs with tentative links to sexual orientation among men.
The University of Miami's Eden Martin and her colleagues genotyped 1,077 homosexual men and 1,231 heterosexual men. As they write in Scientific Reports this week, no SNP reached genome-wide significance for having an effect on male sexuality, though the researchers did find a handful just shy of significant.
One of the stronger associations they uncovered could be traced to a spot on chromosome 13 between the SLITRK6 and SLITRK5 genes. SLITRK proteins, the researchers say, are expressed in the brain, particularly in the diencephalon. New Scientist notes that a 1991 study found that the hypothalamus, which is located in the diencephalon, differs in size in gay and straight men.
The researchers note that their study was limited to men of European ancestry and was small, and say it is a stepping-stone for further studies
The University of Oxford's Gil McVean likewise cautions that the sample size was small, the results haven't been replicated, and they don't meet significance thresholds, according to Newsweek. "I don't think the work would have been published if it were on a less controversial topic," McVean says. "It is — at best — preliminary."