When it was released in 2011, Lady Gaga’s “Born This Way” was the hottest song of the year, topping the charts in 25 countries. It became a gay anthem, with its message that “No matter gay, straight, or bi’, lesbian, transgender life / I’m on the right track, baby”.

That was more than a decade ago.

Whatever has happened to the notion that gays and lesbians are “born this way”, that their sexual orientation is not a matter of choice, but of genetic hard-wiring? The biological model of homosexuality has gone very quiet lately.

There could be a few reasons.

First, with the legalisation of same-sex marriage around the world, homosexuality has been normalised; discrimination has been banned. Just as the debate over the origin of Covid-19 has faded into the background as the disease becomes endemic, endless disputations over an endemic psychological condition seem less urgent.

Second, the transgender movement is sucking the oxygen out of the debate over a biological origin for homosexuality. The whole idea of fluidity is that gender is a choice: you can be whoever or whatever you want to be. Arguing in favour of a fixed sexual orientation has become old-fogeyish.

Third, a major investigation of the question in the leading journal Science in 2019 found that there was no single “gay gene” — which had been the holy grail of this research for decades. The question was still open, according to the researchers, but it appeared that the genetic component to homosexuality was very small. “Same-sex sexual behavior is influenced by not one or a few genes but many,” they wrote. It was the ultimate bad hair day for biological explanations.

Fourth, the search for a biological explanation was a double-edged sword. If a gay gene did exist, it could be detected with rapidly improving testing technology for embryos. Parents might abort a potentially gay offspring. Better not to know at all.

Nowadays, the only place where the biological explanation survives and thrives may be in legislature chambers when “gay conversion therapy” is outlawed. “The consensus in the medical community is ‘yes, we are born that way’,” as one Californian radio station put it. “We can’t change who we are, and we shouldn’t even try.”

But it’s hard to argue that we can’t change unless sexual orientation is genetic. So the hunt for a genetic basis goes on.

The latest development is an article by Australian researchers which appeared a few days ago in The Journal of Sex Research, a leading peer-reviewed academic journal. They used population data from The Netherlands to contend that “having a greater number of older brothers increases the probability of a person entering a same-sex union at some point in their lives”.

In effect, they are proposing, not a genetic cause, but a hormonal one. “This effect has been attributed to a mother’s immune reaction to proteins produced by a male foetus,” they wrote. “The proteins enter the mother’s bloodstream and trigger the production of antibodies that influence the sexual development of subsequent children. These maternal antibodies accumulate over successive pregnancies with male foetuses, which means men with more older brothers are more likely to experience same-sex sexual attraction.”

It’s an ingenious hypothesis – and one that has been proposed before. It’s called the fraternal birth order effect.

What the Australian researchers contribute to the debate is statistical, not medical or genetic. The hormonal explanation is entirely speculative. They found a correlation between the number of older brothers Dutch men born between 1940 and 1990 had and whether they entered a same-sex marriage or civil partnership.

The authors insist that a biological explanation is still important so that gays and lesbians will be fully accepted in society. “People who view sexual orientation as a product of biological factors (such as hormones or genetics) are more likely to support sexual minorities and their civil rights, compared to those who view it as a product of social factors or individual choice,” they write.

MercatorNet asked Dr Paul Sullins, an American sociologist who has written extensively about homosexuality, for a quick assessment of the Australian study. He responded that: “even if the fraternal birth order idea unexpectedly found convincing evidence, it would only explain part of the genetic basis of a minority of male homosexuals. It would not, by itself, re-establish the discarded hypothesis that homosexuality is largely or wholly innate.” Furthermore, he told MercatorNet:

“The idea it embodies is one of a number of early speculations about a possible genetic basis for homosexuality, which included cousin genetics, childhood gender nonconformity, different proposed ‘gay genes’ or genome sequences, lack of exposure to certain hormones in utero, finger length, and other notions long on creativity and hopeful credulity but short on evidence.

“Virtually all of these ideas are dismissed today outside a few true believers in one or more of them due to the advance of solid twin and GWAS [genome-wide association study] evidence showing pretty conclusively that a) the genetic basis for homosexuality is small compared to environmental contributions and b) what genetic association there is is diffuse, unrelated to any particular discoverable cause.”

It remains to be seen if the Australian study will make a splash. The authors allude to a 2006 Danish study which was also based on population-level data. It found no association between homosexuality and fraternal birth order. In fact, it apparently found the opposite: straight men had a greater number of older siblings. “Heterosexual marriage was significantly linked to having young parents, small age differences between parents, stable parental relationships, large sibships, and late birth order,” the Danish authors wrote.

The hunt for the gay gene continues. Slowly.

Michael Cook

Michael Cook is the editor of MercatorNet. He lives in Sydney, Australia.