The results also call into question the Kinsey Scale, a long-utilized rating scale of sexual attraction developed in part by sex researcher Alfred Kinsey, Ganna said.
“We discovered that the Kinsey Scale, which really places individuals on a continuum from basically exclusively opposite-sex partners to exclusively same-sex partners, is really an oversimplification of the diversity of sexual behavior in humans,” Ganna said.
“That can’t be a single line,” Neale added. “The results are not consistent with that being a single line, but they don’t actually tell us what those other dimensions are” that shape human desire.
Researchers are now considering whether a person’s attraction to men and to women should be considered separate from each other, with the two characteristics shaping the person’s overall sexual identity and desires, Ganna said.
The findings were published Aug. 29 in the journal Science.
The results did show that genetic variation has a stronger influence on same-sex sexual behavior in men than in women, possibly demonstrating the complexity of women’s sexuality, said Melinda Mills, a professor of sociology at Oxford University who wrote an editorial accompanying the new study.
“This reflects voices from the LGBTQ+ (lesbian, gay, bisexual, transgender, queer+) community arguing that a range of sexualities exist,” Mills wrote. “Sexuality is dynamic, with the ability to express and realize sexual preferences, and is thus also shaped and regulated by cultural, political, social, legal and religious structures.”
The five specific genes related to same-sex desire cropped up in odd places, the researchers noted.
“We know that smell has a strong tie to sexual attraction, but its links to sexual behaviors are not clear,” he said.
Another gene was associated with male baldness, which is closely linked to how the body regulates sex hormones and might suggest a relationship between hormone regulation and same-sex desire, Ganna said.
Despite their overall small effect, “these genetic variants could hint at some biological pathways that may be involved in same-sex sexual behavior,” Ganna said.