One of the largest sex differences in human behavior is sexual orientation-on average males tend to be attracted to females whereas females tend to be attracted to males, with only 2–10% of the population same-sex oriented 1.
Overall, results support a role for prenatal androgens, as approximated by digit ratios, in influencing the sexual orientation and GNC of a subset of gay men. Differences were found between non-exclusive and exclusive same-sex attraction and GNC, and ASR group differences on digit ratios do not reach significance when all non-heterosexual men are included in the analyses, suggesting greater heterogeneity in the development of non-exclusive same-sex sexual orientations. We then found that Tops have a lower (male-typical) average right-hand digit ratio than Bottoms, and that among all gay men the right-hand 2D:4D correlated with GNC, indicating that a higher (female-typical) 2D:4D is associated with increased GNC. First, we replicated the finding that gay men with a receptive ASR preference (bottoms) report greater gender nonconformity (GNC) compared to gay men with an insertive ASR preference (tops). ASR was used as a proxy for subgroups because ASR groups tend to differ in other measures affected by brain sexual differentiation, such as gender conformity. Here, we asked whether an indirect indication of prenatal androgen exposure, 2D:4D, differs between subsets of gay men delineated by anal sex role (ASR). However, in humans, retrospective markers of prenatal androgens have only been associated with gynephilia among women, but not with androphilia among men. In this context, our aim was to review and debate the relationship between 2D:4D ratio and sex-steroids activity in children, adolescents and young adults.Īcne Alopecia Digit length ratio (2D:4D) Genitourinary disorders PCOS Sex-steroids.Among non-human mammals, exposure to androgens during critical periods of development leads to gynephilia (attraction to females), whereas the absence or low levels of prenatal androgens leads to androphilia (attraction to males). Nevertheless, its validity has not yet been conclusively demonstrated and is currently debated. In contrast, individuals with Klinefelter syndrome (KS), who have reduced testosterone secretion throughout life, have a mean 2D:4D value similar to those found in female population norms. This tentative theory is partially supported by lower 2D:4D in girls with congenital adrenal hyperplasia (CAH), higher 2D:4D in individuals with complete androgen insensitivity syndrome (CAIS) and a relationship between 2D:4D and polymorphisms in the androgen receptor. It has also been reported that the 2D:4D ratio is correlated negatively with prenatal testosterone levels. Digits in females attain their maximum length at about 2.2 years (dextral subjects) or 5.1 years (sinistral subjects) earlier than those in males and increase slightly with age. This sexual dimorphism in 2D:4D ratios is apparent by 2 years of age and seems to be established early in life, possibly by the 14th week of gestation. This gender difference in digit length ratios has been linked with the in utero balance of androgens to oestrogen. The second-to-fourth digit ratio (2D:4D) has been used as an indirect method to investigate the putative effects of prenatal exposure to androgens, and has been reported to be smaller in males than in females.
0 kommentar(er)
