Congenital adrenal hyperplasia (CAH)

Bei Congenital adrenal hyperplasia (CAH) ist die Hormonsynthese in den Nebennierenrinde gestört, die deswegen statt  Cortisol und Aldosteron vermehrt deren Vorstufen Pregnenolon und  Progesteron ausgeschüttet. Da die geringeren Mengen der eigentlich zu bildenden Stoffe in den passenden Gehirnregionen, zB dem Hypothalamus und die Hypophyse registriert wird, wird doch allgemein die Produktion der Nebennierenrinde hochgefahren, die dann auch vermehrt das Sexualhormon Testosteron ausschüttet. Dieser Effekt tritt bereits im Mutterleib ein und führt daher dazu, dass der Fötus einer erhöhten Testosteronkonzentration ausgesetzt ist. Dies sollte nach der Theorie der hormonellen Prägung der Geschlechter im Mutterleib dazu führen, dass die Mädchen sich insgesamt männlicher verhalten und eher bisexuell oder homosexuell sind.

Diese Effekte werden auch in Studien beobachtet:

We assessed core gender identity, sexual orientation, and recalled childhood gender role behavior in 16 women and 9 men with congenital adrenal hyperplasia (CAH) and in 15 unaffected female and 10 unaffected male relatives, all between the ages of 18 and 44 years. Women with CAH recalled significantly more male-typical play behavior as children than did unaffected women, whereas men with and without CAH did not differ. Women with CAH also reported significantly less satisfaction with the female sex of assignment and less heterosexual interest than did unaffected women. Again, men with CAH did not differ significantly from unaffected men in these respects. Our results for women with CAH are consistent with numerous prior reports indicating that girls with CAH show increased male-typical play behavior. They also support the hypotheses that these women show reduced heterosexual interest and reduced satisfaction with the female sex of assignment. Our results for males are consistent with most prior reports that boys with CAH do not show a general alteration in childhood play behavior. In addition, they provide initial evidence that core gender identity and sexual orientation are unaffected in men with CAH. Finally, among women with CAH, we found that recalled male-typical play in childhood correlated with reduced satisfaction with the female gender and reduced heterosexual interest in adulthood. Although prospective studies are needed, these results suggest that those girls with CAH who show the greatest alterations in childhood play behavior may be the most likely to develop a bisexual or homosexual orientation as adults and to be dissatisfied with the female sex of assignment.

Quelle: Androgen and psychosexual development: Core gender identity, sexual orientation, and recalled childhood gender role behavior in women and men with congenital adrenal hyperplasia (CAH) (Abstract / Volltext)

Um so mehr die Mädchen also in ihrer Kindheit männliches Verhalten gezeigt haben um so eher waren sie mit der Frauenrolle unzufrieden und um so seltener waren sie rein heterosexuell. Das passt zu der Theorie, weil solche Mädchen, bei denen die Hormone am deutlichsten pränatale Auswirkungen gehabt haben eben dann auch später die deutlichsten Zeichen davon sehen lassen müssten.

Diese Beobachtungen bestätigen sich auch bei der Digit Ratio:

The ratio of the length of the second digit (2D) to the length of the fourth digit (4D) is greater in women than in men. Since androgens are involved in most somatic sex differences and since the sexual dimorphism in 2D:4D is stable from 2 years of age in humans, it was hypothesized that finger length pattern development might be affected by early androgen exposure. Human females with congenital adrenal hyperplasia (CAH) are exposed prenatally to higher than normal levels of adrenal androgens, providing an opportunity to test the effects of early androgen exposure on digit ratios. The 2D:4D was calculated for females with CAH, females without CAH, males with CAH, and males without CAH. Females with CAH had a significantly smaller 2D:4D on the right hand than did females without CAH. Males with CAH had a significantly smaller 2D:4D on the left hand than did males without CAH. A subset of six males with CAH had a significantly smaller 2D:4D on both hands compared with their male relatives without CAH. These results are consistent with the idea that prenatal androgen exposure reduces the 2D:4D and plays a role in the establishment of the sex difference in human finger length patterns. Finger lengths may therefore offer a retrospective marker of perinatal androgen exposure in humans.

Quelle: Masculinized Finger Length Patterns in Human Males and Females with Congenital Adrenal Hyperplasia

Diese Studien fügen sich insoweit gut in die anderen Fälle ein, bei denen bestimmte pränatale Hormonlevel Auswirkungen auf geschlechtliches Verhalten hatten.

All diese verschiedenen Punkte formen in der Hormontheorie eine schlüssige Theorie. Hingegen kann eine gesellschaftliche Begründung weder die Vererbbarkeit erklären, noch die Übereinstimmung mit der Digit Ratio, noch die Unterschiedlichen Entwicklungen in Verbindung mit dem jeweiligen biologischen Zustand.