BIRTH-ORDER AND SIBLING SEX-RATIO IN 2 SAMPLES OF DUTCH GENDER-DYSPHORIC HOMOSEXUAL MALES

Two studies were undertaken to confirm the previous findings that homo sexual men in general tend to have a later than expected birth order a nd that extremely feminine homosexual men also tend to have a higher t han expected proportion of brothers (i.e., a higher sibling sex ratio) . Subjects in Study I were Dutch, adult and adolescent biological male patients with gender dysphoria (persistent and recurrent desires to b elong to the opposite sex), who were undergoing treatment with feminiz ing hormones. These comprised 83 patients who reported sexual attracti on to other males (the homosexual group) and 58 who reported sexual at traction to females or equal attraction to males and females (the non- homosexual group). Subjects in Study 2 were Dutch adolescent male pati ents at another hospital. The homosexual group consisted of 21 gender- dysphoric homosexual teenagers referred to a gender identity clinic fo r children and adolescents. The control group were 21 adolescent males referred to the child psychiatry department of the same hospital for reasons other than gender identity disorder homosexuality, or transves tism. These were individually matched to the homosexual subjects on ag e and sibship size. In both studies, the homosexual group had a signif icantly later average birth order than the comparison group. In Study 1, the homosexual group had a significantly elevated sibling sex ratio ; this was not tested in Study 2 because of its small sample size. The se studies add to the mounting evidence that late birth orders are com mon to all homosexual samples and that elevated sibling sex ratios are air additional characteristic of extremely feminine ones.