The exact role of genetic involvement is sexuality and sexual preferences have been a very controversial and intriguing topic. Some scientists have been on the search for a singular "gay gene" but a team of scientists lead by Andrea Ganna have found that multiple genes contribute to nonheterosexual behavior.
While there has been evidence that same-sex sexual behavior has a genetic component, such as twins being born with the same sexual orientation, this is the first time that a large-scale study has been done to "identify genetic variants associated with same-sex sexual behavior. For the study, the genomes of 493,001 participants from the U.S., U.K., and Sweden were used to discover any genetic involvement for sexual preference.
The study revealed that specific locations within the genome are associated with homosexual behavior, but not a particular "gay gene" as was popular belief. Ganna et al. "established that the underlying genetic architecture is highly complex; there is certainly no single genetic determinant". The variations in the genome known as SNPs (single-nucleotide polymorphisms) were compared to determine any correlation between them and sexual preference or behavior revealed by the participant. "We identified two genome-wide significant signals for same-sex sexual behavior", Ganna et al. writes. They reveal that by comparing the SNPs and the behavior traits that "same-sex sexual behavior, like most complex human traits, is influenced by the small, additive effects of very many genetic variants".
This study not only reveals important genetic components, that collectively may contribute the same-sex sexual behavior, but it also provides a crucial reminder that there is no simple conclusion that can be made about anything in science today. It is important to remember this going forward; nature vs. nurture will never be a clear line.
To see a news report about this study, watch this video below from CBS News.