What Causes a Person to Have a Particular Gender Identity?
The fact of the matter is that nobody really knows. There are many different theories ranging from genetic (nobody has found a gene for gender identity, transgender or transsexuality) to changes in brain structure (although there is no evidence yet) to hormonal effects in the uterus while the baby is developing, and finally to social and even evolutionary factors. Like most things, gender identity is probably defined through a collection of complex interactions between many variables. In the end, no particular cause/factor has been found to fully support any of these theories.
