I recently came across The boy who was turned into a girl a BBC documentary, first broadcast in 2000, about the David Reimer case:
David Reimer was born male, but his penis was destroyed during a bungled circumcision operation. Under the guidance of now notorious psychiatrist Dr john Money, he was surgically reassigned to female and brought up as a girl. At the time, his case was believed to be a resounding success, proof that people are born gender neutral, and can be molded to identify as either male or female depending on their upbringing. His case became the basis for a policy of carrying out reassignment surgery on babies born intersexed or with otherwise damaged genitals, and thousands of unfortunate infants were operated on as a result.
It had recently emerged that David Reimer's reassignment had failed disastrously, which is what led to the documentary being produced. In it, David talks about how badly his life had been affected, that he had never felt like a girl or been comfortable with a female gender identity, and was now living as a man. Sadly, he committed suicide four years after this documentary was produced.
One thing that particularly interested me, is that they explain in quite a lot of depth about how important testosterone is in driving male brain development. They show some actual footage of female lab rats that were prenatally exposed to testosterone (by injecting the hormone into the mother), adopting male behaviour and attempting to copulate with other female rats. They also show some photomicrographs of brain tissue, demonstrating how the brains of these artificially androgenized female rats have a "sexually dimorphic nucleus" that looks completely different from a normal female one and virtually identical to a male one. I think those experiments provide a good illustration for how being prenatally exposed to hormones with antiandrogenic properties (such as DES) could give rise to MTF transsexuality, and those with androgenic properties (such as first generation progestins) could cause FTM transsexuality.
