Here’s some more evidence that sexuality is an innate characteristic: Gay men are more likely to respond to male sex pheromones than they are to female ones.
It’s not something that should be all that surprising, given what we already know about sexuality in general. But more evidence never hurts. Chinese researchers studied the pheromones naturally given off by men and women in things such as semen, sweat, and urine. Scientists have been aware of the existence of two distinct pheromones—androstadienone (found in male semen and sweat) and estratetraenol (present in female urine)—for some time, but it’s been unclear whether they’ve had much of an effect on the opposite gender. It turns out that they do, and how they do depends on a person’s sexuality.
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To test their hypothesis, Wen Zhou of the Chinese Academy of Sciences set up an experiment in which participants looked at a video in which human figures rendered in a connect-the-dots style (shown above) were shown walking. Participants were then asked to guess whether the figures were masculine or feminine. When exposed to androstadienone, heterosexual women were more likely to suggest that the wire figure was a man—but the pheromone had no effect on heterosexual men.
Perhaps most importantly, homosexual men also responded to that pheromone, suggesting that gay men innately perceive (and are perhaps affected by) male pheromones.
Straight men, meanwhile, were more likely to perceive the figure as feminine when exposed to estratetraenol. Straight women showed no effect, while lesbian and bisexual women showed a response somewhere in between. To keep everything on the straight and narrow, the pheromones were masked with the smell of cloves in all cases.
“We were able to demonstrate qualitatively that androstadienone signals masculinity to heterosexual males and homosexual males, whereas estratetraenol signals femininity to heterosexual males, without the recipients being aware of the odors,” Zhou wrote in a study about his findings, published in Cell. “Importantly, the specific sexual information conveyed by androstadienone and estratetraenol strongly supports them as human sex pheromones.”
Essentially, the findings suggest that humans can “perceive” someone’s biological sex based on these pheromones, but that the effect only works with those people a person might be attracted to. Again—the study did not have any transgender participants.
Participants’ sexuality was measured using the Kinsey Scale, a 0-6 spectrum, with 0 being “exclusively heterosexual” and 6 being “exclusively homosexual.” Each of the 24 straight men and the 24 straight women had Kinsey scores of 0, the 24 gay men, for the purposes of the study, had a mean Kinsey score of 5.25, and the 24 gay or bisexual women had a mean Kinsey score of 4.5.
The study is similar in its findings—if not its methods—to one published in Proceedings of the National Academy of Sciences in 2005 that found that the brains of gay men respond in a similar way to straight women when exposed to androstadienone. Like most pheromones, these two operate essentially subconsciously, but are still an important part of how humans act and perceive each other.
“Such chemosensory processing operates below awareness yet significantly modulates visual gender perception, indicating itself as part of the human gender code in the brain,” Zhou wrote.
Frankly, it shouldn’t matter how one becomes gay, straight, bi, or any other sexual orientation—but in a world where gay-to-straight conversion camps are still a thing, any scientific findings like this shouldn’t hurt.
