In 1993, researchers found that a stretch of DNA on the X chromosome was linked to male homosexuality. This stretch of DNA was popularly called as the "gay gene" in the media, causing significant controversy within the public and inspiring a lot of follow-up studies over the years.
But the latest study published on the journal Science found that there is no single "gay gene" that can decide someone's sexual orientation.
About the study
For the study, the researchers studied the genetic profiles of nearly 480,000 people from the United States and the United Kingdom, a group approximately 100 times larger than any previous study of the link between genetics and same-sex attraction.
There is no "gay gene"
The researchers found five specific genetic variants that were significantly associated with same-sex behavior, but none was reliable enough to decide someone's sexuality. Overall, genetic factors could explain 8–25% of the variation in sexual behavior.
"It's effectively impossible to predict an individual's sexual behavior from their genome," said the researcher Ben Neale. "Genetics is less than half of this story for sexual behavior, but it's still a very important contributing factor. These findings reinforce the importance of diversity as a key aspect of sexual behavior."
Besides, the researchers found some odd things about these five specific genes. For example:
—One gene was related to the sense of smell.
—Another gene was related to male baldness.
This suggests that there may be a relationship between hormone regulation and same-sex desire.
Sexual orientation is a normal piece of the human experience
GLAAD (the Gay & Lesbian Alliance Against Defamation), the world's largest LGBTQ advocacy group, said the results show that being gay or lesbian was a natural part of human life.
"The identities of LGBTQ people are not up for debate. This new research also reconfirms the long-established understanding that there is no conclusive degree to which nature or nurture influence how a gay or lesbian person behaves," said GLAAD Chief Programs Officer Zeke Stokes.
The results also call into question the Kinsey Scale.
What is Kinsey Scale?
The Kinsey scale, also called the Heterosexual–Homosexual Rating Scale, is used in research to describe a person's sexual orientation based on one's experience or response at a given time.
The scale typically ranges from 0 to 6. 0 means one is exclusively heterosexual while 6 means one is exclusively homosexual.
But a person's attraction to those of the same sex is shaped by a complex mix of genetic and environmental influences, so Kinsey scale is actually an oversimplification of the diversity of sexual behavior in humans.
Researchers are now considering whether a person's attraction to men and to women should be considered separate from each other, according to lead researcher Andrea Ganna.
Many questions are still unanswered
The study leaves many questions unanswered, but it is still important to tell people that there is no so-called "gay gene".
"This is a natural and normal part of variation in our species, and that should also support the position that we shouldn't try and develop gay cures. That's not in anyone's interest," said Neale.