In the end, the scientists could not find any genetic patterns that could be used, in any way, to identify a person's sexual orientation. Instead, the predisposition to same-sex sexual behavior appeared influenced by a complex mix of genetic and environmental influences. That's also the case for many other human traits, such as height.
"It's effectively impossible to predict an individual's sexual behavior from their genome," study co-author Ben Neale, a statistical geneticist at the Broad Institute of MIT and Harvard, told Live Science.
However, the finding that there's no single gay gene does not mean that sexual orientation is not genetic or biological, and is therefore a lifestyle choice.
"This is wrong," study co-author Brendan Zietsch, a geneticist at the University of Queensland in Australia, told Live Science. "We find that there are many, many genes that predispose one to same-sex sexual behavior. Each of them individually has a very small effect, but together they have a substantial effect.
"Another possible misinterpretation is to think that if same-sex preference is genetically influenced, it must therefore be totally genetically determined," Zietsch added. "That is not true. Genetically identical individuals — twins — often have different sexual orientations. We know there are non-genetic influences as well, but we don't understand these well, and our study does not say anything about them."