Are gays born that way? New research presented Thursday at the American Association for the Advancement of Science in Chicago looks at this question.
The findings were presented by Michael Bailey, a Northwestern University psychologist who has been sharply criticized by both conservatives and the LGBT community in the past for his research, writing and classes.
He reported that his research shows, according to The Telegraph's science correspondent Sarah Knapton, that some gay men share certain genetic characteristics on a region of the X chromosome called Xq28.
The study could not determine which genes in the Xq28 region seemed to have an impact on same-sex attraction. Those with this genetic signature had about a 40 percent of chance of identifying themselves as gay.
Not all gay men have the genetic marker and not all those with the genetic marker are gay. This finding is consistent with prior research that also suggests genetics might play a role in same-sex attraction, but the role is not determinative.
Research conducted by Bailey and Richard Pillard conducted in the early 1990s similarly showed that the identical twin of a gay man (they share the same DNA) is more likely to be gay than a male randomly chosen from the population. The identical twin of a gay man is not always gay, though. Additionally, other studies have shown that adoptive brothers of gay men are even more likely to be gay than the identical twins of gay men, suggesting that environmental factors play a larger role. Plus, there is no evidence of a similar gene in lesbians.
In other words - it is complicated. Researchers do not really know why some people have same-sex attractions and others do not. There are many questions and few answers. More research is needed to answer the question of what causes same-sex attraction.
"Sexual orientation has nothing to do with choice," Bailey insisted. But, he immediately followed that with more humble remarks noting the limitations of his findings.
"Our findings suggest there may be genes at play - we found evidence for two sets that affect whether a man is gay or straight. But it is not completely determinative; there are certainly other environmental factors involved. The study shows that there are genes involved in male sexual orientation. Although this could one day lead to a pre-natal test for male sexual orientation, it would not be very accurate, as there are other factors that can influence the outcome," he said.
The public appears deeply interested in the question of what makes people gay. Even though the research has yet to be published in a peer-reviewed journal, or even posted online for the public to review it, it has been widely reported based solely upon news reports from Bailey's conference presentation.
Bailey previously came under fire from the LGBT community for his 2003 book, The Man Who Would Be Queen, in which he suggests there are two distinct types of transgender people - those who experience an extreme form of homosexuality and those who become sexually aroused by the thought of being dressed as a woman.
He was also sharply criticized, mostly by conservatives, in 2011 when his human sexuality class hosted a guest speaker who personally demonstrated a homemade sex toy made from a reciprocating saw.