Abstract
Among the siblings of homosexuals, a lack of sexual and romantic interest in women may be independent of erotic feelings for men. This study investigated the sexual histories of siblings of gender-dysphoric outpatients. The patients were classified into three groups: non homosexual males, homosexual males and homosexual females. Their siblings consisted of 301 brothers and 284 sisters over the age of 25. Logistic regression showed that the brothers of the homosexual male patients were significantly less likely to have been married, either legally or common-law, than the brothers of the other gender-dysphoric groups, even with age and relative birth order taken into account. This finding suggests that the low propensity for long term heterosexual relationships seen in homosexual male gender-dysphoric patients also tends to appear in their brothers.