According to Australian researchers discovery of a genetic variation in male to female transsexuals has added weight to the view that it has a biological basis. Their study has shown that male to female transsexuals are more likely to have a longer version of a receptor gene for sex hormone androgen and testosterone than non-trans-sexual males.
The findings from so far the largest genetic study of male to female trans-sexualism was published online today in Biological Psychiatry. Leader of the study, Professor Vincent Harley has speculated that this genetic variation might reduce testosterone action and "under-masculinise" or feminise the during foetal development. “Studies in cells show the longer version of the androgen receptor gene works less efficiently at communicating the testosterone message to cells. Based on these studies, we speculate the longer version may also work less efficiently in the brain" said Harley.
Researchers suggested reduced androgen and its signalling contributes to the female gender identity of male to female transsexuals. “It is possible that a decrease in testosterone levels in the brain during development might result in incomplete masculinisation of the brain in male to female transsexuals, resulting in a more feminised brain and a female gender identity," they said.
People develop an inner sense of being male or female from an early age but transsexuals identify with a physical sex opposite to their biological sex. Some theories suggest some causes that include psychosocial factors including dysfunctional family dynamics and traumatic childhood experiences. But research is increasingly implicating biological factors including family history and genetics.
The present study would disapprove the social stigma that trans-sexualism is simply a lifestyle choice, the findings support a biological basis of how gender identity develops.