There Is No ‘Gay Gene,’ Comprehensive Scientific Study Finds, by Matt Margolis.

The belief that sexual orientation is innate has been crucial to the gay rights movement.

According to the most recent Gallup Poll on the subject, 88 percent of people who believe homosexuals are “born that way” support the legality of same-sex marriage, while only 39 percent of those who believe homosexuality is the result of environmental factors support the legality of same-sex marriage.

No ‘gay gene’, but study finds genetic links to sexual behavior, by Kate Kelland.

The research, which analyzed data on DNA and sexual experiences from almost half a million people, found there are thousands of genetic variants linked to same-sex sexual behavior, most with very small effects.

Five of the genetic markers were “significantly” associated with same-sex behavior, the researchers said, but even these are far from being predictive of a person’s sexual preferences.

“We scanned the entire human genome and found a handful — five to be precise — of locations that are clearly associated with whether a person reports in engaging in same-sex sexual behavior,” said Andrea Ganna, a biologist at the Institute of Molecular Medicine in Finland who co-led the research.

He said these have “a very small effect” and, combined, explain “considerably less than 1% of the variance in the self-reported same-sex sexual behavior.”

This means that non-genetic factors — such as environment, upbringing, personality, nurture — are far more significant in influencing a person’s choice of sexual partner, just as with most other personality, behavioral and physical human traits, the researchers said.

The study — the largest of its kind — analyzed survey responses and performed analyses known as genome-wide association studies (GWAS) on data from more than 470,000 people who had given DNA samples and lifestyle information to the UK Biobank and to the U.S. genetics testing company 23andMeInc. …

“Previous studies were small and underpowered,” Ganna said. “So we decided to form a large international consortium and collected data for (almost) 500,000 people, (which) is approximately 100 times bigger than previous studies on this topic.”

A gay orientation might be determined by conditions in the womb, such as inappropriate amounts of the various sex hormones at the crucial period about six weeks after conception. This is when the part of the brain that determines sexual orientation is being formed.

So, gays might be “born that way” even though it is not genetic.