A study conducted by an international group of scientists working with 23andMe, a personal genomics firm, has confirmed that homosexuals aren’t “born that way” and that human sexuality is the consequence of a complex interplay between genetic and environmental factors. Genetic factors accounted for at most 25% of same-sex behaviour.
The study used a genome-wide association study (GWAS) on 408,995 individuals in the UK Biobank, a British health resource, and 68,527 American 23andMe users, all of whom remained anonymous and consented to the study.
“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 behaviour,” 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 behaviour.”
The researchers said that this means that environmental factors, such as upbringing, nurture, environment, and others played a much more significant role in determining an individual’s sexual behaviour, as it also happens in case of any other personality and behavioural trait.
“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.”
The study has been welcomed by LGBT advocacy groups saying it “provides even more evidence that being gay or lesbian is a natural part of human life”. “This new research also re-confirms the long-established understanding that there is no conclusive degree to which nature or nurture influence how a gay or lesbian person behaves,” said Zeke Stokes of the US-based LGBTQ rights group, GLAAD.