Dec. 8, 2017 (Medical Xpress) -- Scientists have found two gene variants that appear to be more prevalent in gay men than straight men, adding further evidence of sexual orientation having a biological component.
In their paper published in Scientific Reports, the large team of researchers from several institutions in the United States, and one each from Australia and the U.K., describes their study, which consisted of comparing the genomes of multiple gay men against multiple straight men.
The results represent the first identification of specific genes as perhaps influencing sexual orientation in males. The finding was made as part of a study of DNA samples from 1,231 straight men and 1,077 gay men. The team reports that they did not focus exclusively on any one part of the genome, instead scanning the entire genome looking for differences in single letters rather than whole chromosomes, as has been done in the past. Doing so, the team further reports, allowed them to identity two gene variants that seemed to be linked to sexual orientation.
One of the genes is located on chromosome 13, which prior research has shown has an impact on the diencephalon, a part of the hypothalamus -- a part of the brain shown to be differently sized between gay and straight men. The other gene was found on chromosome 14, which prior research has shown is mainly involved with the thyroid, though it does also have an impact on the brain via a protein involved in stimulating the thyroid. Some prior studies have led to findings that suggest the thyroid might also be involved in sexual orientation.
The findings by the team do not settle the argument of whether homosexuality in people is biology-based, but instead offers more evidence that suggests it is likely the case.