Send to

Choose Destination
Arch Sex Behav. 1993 Jun;22(3):187-206.

Homosexual orientation in twins: a report on 61 pairs and three triplet sets.

Author information

Department of Sociology, Arizona State University, Tempe 85287-2101.


Twin pairs in which at least one twin is homosexual were solicited through announcements in the gay press and personal referrals from 1980 to the present. An 18-page questionnaire on the "sexuality of twins" was filled out by one or both twins. Thirty-eight pairs of monozygotic twins (34 male pairs and 4 female pairs) were found to have a concordance rate of 65.8% for homosexual orientation. Twenty-three pairs of dizygotic twins were found to have a concordance rate of 30.4% for homosexual orientation. In addition, three sets of triplets were obtained. Two sets contained a pair of monozygotic twins concordant for sexual orientation with the third triplet dizygotic and discordant for homosexual orientation. A third triplet set was monozygotic with all three concordant for homosexual orientation. These findings are interpreted as supporting the argument for a biological basis in sexual orientation.

[Indexed for MEDLINE]

Supplemental Content

Loading ...
Support Center