There’s long been something of a debate about this question, and I thought I’d note an interesting and apparently quite credible article touching on it, Nanette K. Gartrell, Henny M. W. Bos & Naomi G. Goldberg, Adolescents of the U.S. National Longitudinal Lesbian Family Study: Sexual Orientation, Sexual Behavior, and Sexual Risk Exposure, Archives of Sexual Behavior (2010). (I learned of it because one of the coauthors is affiliated with the Williams Institute for sexual orientation and the law here at UCLA School of Law.)
The study was part of an ongoing study that, at this stage, involved 77 families, “31 continuously-coupled, 40 separated-mother, and six single-mother families,” and 78 17-year-old children (one family had twins). Of the girls, nearly 50% described themselves as at least partly homosexual in orientation, though 30% out of that 50% were “predominantly heterosexual, incidentally homosexual.” (None of the girls, though, identified themselves as predominantly or exclusively lesbian.) Of the boys, a bit over 20% described themselves as at least partly homosexual in orientation, though 13% out of that 20% described themselves as “predominantly heterosexual, incidentally homosexual.” (Two of the boys identified themselves as predominantly or exclusively gay.) “The … Kinsey self-identifications [of the girls in the study] and lifetime sexual experiences were consistent with Stacey and Biblarz’s (2001) and Biblarz and Stacey’s (2010) theory that the offspring of lesbian and gay parents might be more open to homoerotic exploration and same-sex orientation.”
As to actual sexual behavior, 15% of the girls had had sex with other girls, compared to 5% in a sample of 17-year-old girls at large; 54% of the girls had had sex with boys, compared to 63% in a sample of 17-year-old girls at large. The boys showed no greater participation in homosexual sex compared to the sample of 17-year-old boys at large, but showed a markedly lesser participation in heterosexual sex (38% as opposed to 59%). For both the boys and girls who had had sex, the age of first sexual contact was about a year later than in the samples of 17-year-olds at large. All these differences are statistically significant.
The study has obvious limitations: It’s fairly small (though large enough for the authors to get statistically significant findings). It might be subject to various confounding factors; the families in the study and the comparison families from the population at large “were neither matched nor controlled for socioeconomic status, race/ethnicity, or region of residence.” It doesn’t speak to children of gay men, including children raised by the men either alone or with male partners. It doesn’t tell us what will happen to the 17-year-olds in the future (though a planned follow-up will interview the children when they are 25).
It doesn’t tell us whether the greater propensity to same-sex attraction and behavior among the girls stems from genetics, upbringing, or a mix of both. And even if future studies suggest that the propensity does stem largely from upbringing, that wouldn’t affect my judgment on policy matters (such as whether the parents’ sexual orientations should affect child custody decisions, whether same-sex couples should be allowed to adopt, and so on): I don’t think there’s anything wrong with a child’s having a greater likelihood of growing up to be lesbian or gay, or experimenting with same-sex sexual behavior.
Still, it struck me as an interesting data point on a contested factual question, so I thought I’d pass it along.