OBJECTIVE: The purpose of this study was to determine whether female
homosexuality is familial and whether it is cofamilial with male
homosexuality. METHOD: Subjects included 84 homosexual and 79 heterosexual
female probands recruited through newspaper advertisements. Probands were
asked about their siblings' sexual orientations and were asked for
permission to contact siblings to confirm their reports. RESULTS: The
authors were able to contact 60% of eligible siblings, and the information
they provided about their sexual orientations confirmed that probands'
reports were highly accurate. Homosexual probands had a significantly
higher proportion of homosexual sisters according to four criteria for
rating siblings' sexual orientations. Homosexual probands also had a higher
proportion of homosexual brothers; however, this difference was not
significant. CONCLUSIONS: Female homosexuality appears to be familial.
Further research is required to resolve the question of whether female and
male homosexuality are cofamilial.