The ‘gay gene’ — myth or reality?

29 Sep, 2016


Small, dark and fiercely intelligent, Dr Qazi Rahman speaks quickly and excitedly about his specialist subject — what makes us gay?

Rahman is the assistant professor in cognitive biology at London’s Queen Mary University and I started by asking what that means.

“We’re really looking at what is the function of various human behaviours — for example, why do babies cry?” Rahman explains. “We look to understand the behaviour by asking a series of questions: How does that behaviour increase reproduction? Is it learned behaviour or genetically hard-wired? How does the behaviour develop during your life-span? Is there a similar behaviour in comparable species? I’m using that same framework to try and understand homosexual behaviour — what makes us gay?”

I suggested that watching a lot of Will & Grace might have had something to do with my sexual orientation, but Rahman quickly rubbishes this suggestion.

“Fifty years of psychological research has not been able to document any psycho-social basis or learning of homosexual orientation. Any suggestion that you could decide or learn to be gay is based on the traditional understanding of psychology that believed that everything was learned behaviour. Heterosexuality was seen as the norm and therefore any variation from that was deviant — generally it was some form of ‘failure’ in the parenting of the child that was seen to have led to homosexual behaviour.

“Around the mid-80s and up to the early-90s more detailed research was completed — particularly in relation to to kids who showed early indicators of being ‘different’. This research has shown that differences in parental rearing style, or what parents did to their kids, didn’t predict whether kids would grow up gay.”

What about the notion of the absent or distant father, or the dominant mother?

“In the research, some kids do report fathers being distant but there is a general acceptance that this is likely to be the parent reacting to differences in the child as opposed to the other way around. In relation to the influence of a dominant mother, or Oedipal complex, suggesting that boys were unable to get over their attraction to their mother and therefore become gay — this just doesn’t make any sense and requires leaps in logic that don’t bear any scrutiny.”

So how does Rahman and his fellow scientists define sexual orientation?

“At its most basic level, the question is: Which gender attracts your attention? When you walk into a room does your gaze travel to guys or girls? Sexual orientation is like a rudder — generally an either/or kind of trait. About 95–98% of people are oriented to the opposite sex and can be classified as heterosexual.”

These figures seem low to me and I quiz Rahman on my understanding that we were generally working on a one-in-10 rule.

“That’s a bit of an urban myth based on an interpretation of Kinsey’s ground-breaking research. Based on today’s research it’s more like 2% to 5%.”

I take our conversation back to the starting point of what makes us gay. Rahman’s research is exploring a number of theories:

“We know that there is no such thing as a ‘gay gene’, but there could be a combination of genes that leads to a guy being attracted to males. Research has shown us that one in seven gay men owe their sexual orientation to having an older brother. Each older brother increases your chance of being gay by 33%, and so the more older brothers you have the more likely you are to be gay.”

"What we don’t know is why that is the case — we think it might be that the mother’s immune system forms antibodies against male proteins in the developing foetus potentially making the brain more feminine. It’s just a theory but there is some interesting research that suggests that it’s part of the picture.”

“We also know that gay men generally come from larger families, not just immediate but extended, primarily on the mother’s side. One of the theories being explored is that the evolution of homosexuality provides some sort of reproductive advantage to the relatives of gay people. For example the female relatives of gay men appear to be more reproductive than those females without gay men in their family.”

Cognitive biology looks at what comparable species can tell us about human behaviour so what does this tell us about homosexuality?

“Loads of animals exhibit same-sex behaviour, but we don’t have any other comparable species that show life-long same-sex orientation as we know it in humans…” Rahman explains. “While there are no comparable species, we do see it in some. For example 5%–10% of male sheep will consistently only go for other male sheep — even if other options are presented. Zebra Finches also consistently demonstrate life-long same-sex orientation. But amongst primates humans are quite unique in this sense.”

“For me, the big question is evolutionary. Why does a trait like homosexuality, which is non-reproductive, persist in evolution when natural selection should have got rid of it? Genes for homosexuality exist but gay men who rarely have biological children are not passing these genes on, so why does it exist?”

This is one line of research definitely worth keeping an eye on.