AUSTRALIA — Although it’s popular with certain religious and philosophical groups to blame non-“traditional” sexual behavior upon poor upbringing, a lack of moral character, too much soy in the diet or other creative reasons, science appears a little closer to understanding why some people born male yearn to live as women. In a word: androgen. According to DNA analysis performed on 112 male-to-female transsexual volunteers, those who participated exhibited notably longer versions of the androgen receptor gene than do those in the general population.
What this may well mean is that testosterone signals were weaker for the 112 studied. This and other studies have suggested that, when coupled with other genetic variables, a wide range of behaviors can result, including “female-like” brain structures in those men who identify or yearn to identify as female.
As recounted by researchers in Biological Psychiatry, three genes involved with sexual development were studied: coding for the androgen receptor, the estrogen receptor and an enzyme that converts testosterone to estrogen.
When the DNA from male-to-female transsexuals was evaluated, the existence of a long estrogen receptor was identified as likely to be involved with the participants’ development of sexual identity.
The association between a longer androgen receptor and less efficient testosterone signaling has been known for some time. Researchers conjecture that its effect on gender identity development may begin within the womb.
As researcher Lauren Hale of Prince Henry’s Institute of Medical Research explains it, “We think that these genetic differences might reduce testosterone action and under masculinise the brain during fetal development.”
Hale and co-author Vincent Harley hope to take their research, the most comprehensive to date, to an even larger population in hopes of replicating their results.
Harley understands the potential importance of his research, pointing out that “There is a social stigma that transsexualism is simply a lifestyle choice, however, our findings support a biological basis of how gender identify develops.”
