The biggest study to date regarding the genetic basis of sexuality has shown five spots on the human genome that are linked to same-sex sexual behavior — however, none of the markers are reliable enough to predict one’s sexuality reports the Nature International Journal of Science.
The findings that were published on Thursday, were based on the genomes of almost 500,000 people, support the results of earlier, smaller studies while confirming the suspicions of a lot of scientists: although sexual preferences possess a genetic component, no single gene has a significant effect on sexual behaviors.
“There is no ‘gay gene’,” said lead study author Andrea Ganna, a geneticist at the Broad Institute of MIT and Harvard in Cambridge, Massachusetts.
Ganna and his fellow researchers also utilized the analysis to estimate that as much as 25% of sexual behavior can be explained by genetics, while the rest is influenced by both environmental and cultural factors — a figure that matches the findings of smaller studies.
“This is a solid study,” says Melinda Mills, a sociologist at the University of Oxford, UK, who studies the genetic basis of reproductive behaviors.
However, she also cautions that the results might not be representative of the overall population. This is a limitation that the study’s authors acknowledge. The vast majority of the genomes are from from the UK Biobank research program as well as the consumer-genetics company 23andMe, based in Mountain View, California. Those who offer their genetic and health information to those databases are of predominantly European ancestry. They are also on the “older side”. UK Biobank participants were between the ages of 40-70 years old at the time that their data was collected, and the average age for people in 23andMe’s database is 51.
The study’s authors also note that they followed the convention for genetic analyses by eliminating people whose biological sex and self-identified gender didn’t match from their study. The result – the work does not include sexual and gender minorities (the LGBTQ community).