In this article, we evaluate the status of current biological research into sexual orientation and examine the relevance of such research on the legal and social status of gay men and lesbians. We begin with a review of hormonal neuroanatomical and genetic studies of sexual orientation. We argue that the scientific study of sexual orientation is, at best, still in its infancy. We turn then to the ethical and social implications of this research. We argue that even if scientists could explain how sexual orientation develops, no significant ethical conclusions would follow. Further, we suggest that the current emphasis on finding a biological basis for sexual orientation is potentially harmful to lesbians, gay men and other sexual minorities in various ways (although perhaps it is in some ways potentially helpful as well).