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A new study published this month by Wen Zhou of the Chinese Academy of Sciences found a connection between a person’s self-identified sexual orientation and their ability to react to different pheromones. Specifically, participants with an orientation to men (straight women and gay men) responded to male pheromones but not female pheromones.
The experiment exposed participants to either androstadienone (found in male semen and sweat) or estratetraenol (present in female urine) and tested to see how it impacted their gender presentations of a simulated person walking toward them. In all cases, the pheromones were disguised by cloves, so participants were unaware of which pheromone (if any) they were smelling. Self-identified gay men and straight women were more likely to perceive masculinity when exposed to the male pheromone, but had no reaction to the female pheromone. Conversely, straight men were more likely to perceive femininity when exposed to estratetraenol, while lesbian and bisexual women had a more mixed reaction.
According to Zhou, the study confirms that androstadienone and estratetraenol are in fact human sex pheromones that communicate information about gender. While it’s not clear how or why the sense of smell perceives this gender information, the fact that results differed based on participants’ sexual orientation provides further evidence that there is a biological component to sexuality.
This result jibes with a 2005 study that similarly analyzed how these pheromones impact sexual arousal in the brain. Straight men perceived the female pheromone as arousing and the male pheromone as simply an odor, while both gay men and women perceived the male pheromone as arousing and the female pheromone as simply an odor. That study did not specify the results for gay women, because the data were apparently “somewhat complicated” and not yet ready for publication.
Biological connections to sexuality have also been demonstrated through genetic research. A study published in 2012 found that there may be “epi-marks” on genes that can be triggered during fetal development by hormones in ways that can impact sexual identity and gender characteristics. Researchers have also recently found certain genetic signatures that gay men have in common, suggesting another genetic component to the complex question as to what determines sexual orientation.