Read the BBC article here:
See the report article here (Science: Melinda C Mills)
A genetic analysis of almost half a million people has concluded there is no single "gay gene".
The study, published in Science, used data from the UK Biobank and 23andMe, and found some genetic variants associated with same-sex relationships.
But genetic factors accounted for, at most, 25% of same-sex behaviour.
Advocacy group GLAAD said the study confirmed "no conclusive degree to which nature or nurture influenced how a gay or lesbian person behaves."
The researchers scanned the genomes - the entire genetic make-up - of 409,000 people signed up to the UK Biobank project, and 68,500 registered with the genetics company 23andMe.
Participants were also asked whether they had same-sex partners exclusively, or as well as opposite-sex partners.