The study, by far the largest such investigation of sexuality to date, was made possible by combining genetic and behavioral data from more than 400,000 people from the UK’s BioBank study, and from 70,000 customers of the genetic testing company 23andMe, who opted in to having their data used for research. The team combed the genomes of more than 470,000 people in the United States and the United Kingdom to see how genetic variants at millions of different places in the genome correlate with whether participants had ever had sex with someone of the same sex. That’s the conclusion of a paper by an international team of researchers, co-led by Benjamin Neale of the Broad Institute of Harvard and MIT, published today in the journal Science. There is no one gene for being gay, and though genes seem to play a role in determining sexual orientation and same-sex behavior, it’s small, complex, and anything but deterministic.