From Queer Day:
The locations of genes influencing male sexual orientation have been identified in a genome analysis of men in families with multiple gay brothers. The research confirms the biological origins of homosexuality while underscoring that there is no single “gay gene” as some have tried to tell us. “Sexual orientation is a complex trait, so it’s not surprising that we found several DNA regions involved in its expression,” says researcher Brian Mustanski of the University of Illinois at Chicago. Working with colleagues at the National Institutes of Health, Mustanski analyzed the genome of 456 men from 146 families with two or more gay brothers. Unlike earlier studies focusing just on the X chromosome, this study looked at the X as well as all 22 pairs of non-sex chromosomes. The researchers found identical strings of DNA on chromosomes 7, 8 and 10 that were shared by 60% of gay brothers in the study.