In a new study, researchers found that there is no single “gay gene” that could determine one’s sexual orientation.
They found a person’s attraction to those of the same sex is shaped by a complex mix of genetic and environmental factors.
This is the largest genetic study ever conducted on the issue.
The research was conducted by an international team from the United States and the United Kingdom.
Across human societies and in both sexes, some 2% to 10% of individuals report engaging in sex with same-sex partners, either exclusively or in addition to sex with opposite-sex partners.
Twin and family studies have shown that same-sex sexual behavior is partly genetically influenced, but previous searches for the specific genes involved could not effectively detect effect sizes realistic for complex traits.
The current study examined the genetic profiles of 477,522 people from the United States and the United Kingdom.
The participant group was about 100 times larger than any previous study of the link between genetics and same-sex attraction.
The team discovered five specific genetic variants that were significantly associated with same-sex behavior, but when combined these variants explained less than 1% of any person’s attraction to their own gender.
The team says genetic factors account for between 8% and 25% of a person’s same-sex attraction and thousands of genetic traits ultimately are involved in shaping a person’s sexual desires.
It is impossible to predict one’s sexual behavior from their genome. Genetics is less than half of this story for sexual behavior, although it is an important contributing factor.
Other researchers suggest that sexual orientation is just another normal piece of the human experience.
The team says many uncertainties remain to be explored, including how sociocultural influences on sexual preference might interact with genetic influences.
The lead author of the study is Andrea Ganna, a research fellow with the Massachusetts General Hospital’s Analytical and Translational Genetic Unit.
The study is published in Science.
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