A biologic perspective on sexual orientation.
Pillard RC, Bailey JM.
Department of Psychiatry, Boston University School of Medicine, Massachusetts, USA.
Sexual orientation may be defined as the sustained erotic attraction to members of one's own gender, the opposite gender, or both--homosexual, heterosexual, or bisexual, respectively. Interest in sexual orientation is as old as the science of psychology, yet many fundamental issues remain unresolved. This article reviews research in the development and psychopathology of sexual orientation as well as the results of family and twin studies. Research in genetic linkage, sex hormones, and brain differences also is discussed.
PMID: 7761309 [PubMed - indexed for MEDLINE] >>>>
Heritable factors influence sexual orientation in women.
Bailey JM, Pillard RC, Neale MC, Agyei Y.
Department of Psychology, Northwestern University, Evanston, Ill 60208.
Homosexual female probands with monozygotic cotwins, dizygotic cotwins, or adoptive sisters were recruited using homophile publications. Sexual orientation of relatives was assessed either by asking relatives directly, or, when this was impossible, by asking the probands. Of the relatives whose sexual orientation could be confidently rated, 34 (48%) of 71 monozygotic cotwins, six (16%) of 37 dizygotic cotwins, and two (6%) of 35 adoptive sisters were homosexual. Probands also reported 10 (14%) nontwin biologic sisters to be homosexual, although those sisters were not contacted to confirm their orientations. Heritabilities were significant using a wide range of assumptions about both the base rate of homosexuality in the population and ascertainment bias. The likelihood that a monozygotic cotwin would also be homosexual was unrelated to measured characteristics of the proband such as self-reported history of childhood gender nonconformity. Concordant monozygotic twins reported similar levels of childhood gender nonconformity.
PMID: 8439243 [PubMed - indexed for MEDLINE]