While I understand and agree with the sentiment I don't like the implications of your reasoning. There is a hint there of not trusting the person interviewed. While I would agree with a mistrust of the angling and data selection of a documentary which could be biased, I do usually trust the interviewee (?) when they tell their life story. It depends on the mood of the program.
As i have said above, the story about the transman was nothing unusual if we just take the chain of events you described. I know at least two transmen who would tell a very similar story, and none of them say that his gender identity has actually changed.
I've personally dealt with the question whether my gender identity changed a couple of years ago (to what it know is) - and it just wouldn't make sense if i would claim that i has, because there is neither mechanism nor cause for such a change.
That's my main argument against gender identities actually changing (instead of just appearing to change): Psychologists have looked for social causes of gender identity for the last 60 years or so, and they have found no mechanisms or causes for such a change. They have not even found a mechanism that supports any claim that gender identity is purely based on social influences.
Put simply - you can't raise a biological, non-transsexual boy as a girl no matter how hard you try (even if you alter the body accordingly). It has been tried several times and failed every single time (and vice versa for cisgirls).
Also, no one has found any social causes for transsexuality - you can be raised by a tolerant or intolerant family, by a famility with a dominant father or mother or a well-balanced relationship, as a single child or with siblings of one or both genders, you can be a first, intermediate or last child, you can have lot's of friends of the same or opposite gender or both, you can be allowed to play with dolls or trucks or not, you can be raised by a single parent of either gender or not, you can have grandparents or your parent is your only family, you can be raised wealthy or poor, you can be neglected or get a lot of attention and so on and so on and so on.
NONE of these things have been shown to have ANY significance for transsexuality. If gender WAS purely based on socialisation, then we should find one or several strong influences that cause transsexuality - perhaps 30% of all transsexuals were raised by a single parent of the same gender, or perhaps 26% were neglected during a specific phase in childhood. But we have found NOTHING like that.
Now of course you can say that this doesn't mean that we will never find anthing - but when people have looked for fourty years and found absolutely nothing, then i think it's pretty fair to consider other explanations to be superior. If we actually find a social cause, that would change things - but if the evidence can't support a theory, it is obviously quite weak.
Don't know any transmen and since its so much less covered (and rarer I think?) my exposure is low. But if you say its a common story then my opinion of it being changeable is reinforced rather than the opposite.
Except that none of them describe their gender identity as having changed. Rather, it's all about having a male gender identity all along and trying to find a way that allows them to live according to that identity and still fit with what everyone is telling them (that they're women). This mostly happens unconciously, but it can also be a concious effort.
I stronly suspect that the documentary constructed "realizing someones own gender identity" as "changing someones own gender identity". This is a rather common mistake - many transsexual people try to display the gender identity society tells them they should have until their transition. A few years ago, other people would have perceived me as having a male gender identity, and i would have likely confirmed that if they had asked - i just tried to conform that hard. Now that's not the case anymore - people perceive me as having a female gender identity and i say so when asked.
That doesn't mean that my gender identity has changed, it only means that my behaviour has changed. The male gender identity is was displaying earlier in my life was just acting - very elaborate and unconcious acting, but acting nontheless. And it showed, i was solely copying other peoples behaviour, was insecure when i could not do that and so on. That's another thing that has amazingly changed - a lot of my female behaviour came much more sponataneous, and i am much less insecure about it.
Now i have seen the same thing happen to other transwomen and to transmen. A transman i know got the chance to drop his female act about a year ago (he moved out from his parents). He was quite capable of acting female before that, but it always felt slightly detached from his actual personality. But afterwards, this was not the case when he was acting male. It was sometimes a bit strange, like a young teenage boys behaviour, but it didn't feel like acting. And that stopped after a few months, and he is now acting genuinenly all the time - as a man.
As i said, i strongly suspect that this is what happened to the transman in your documentary as well. It fits all the facts given there and it also fits my own observations.
Oh, and by the way, it is very likely that there are about as many transmen as transwomen. Official statistics tend to say that there are three times more of the latter than of the former, but they are horribly outdated and inaccurate.
It's just that you won't notice transmen on the streets - early in their transition, you'll perceive them as a butch lesbian or a feminine man. And once they had testosterone for about a year, you won't notice a thing, except possibly their small body height and slightly slender built.
But if it is buried so deep that the person doesn't know about it and there never is a triggering event for such emotions/mindset then I'd argue that that person is not a transsexual at all. I would also be very suprised if you post-mortem could determine that that should have been a transsexual.
When you bury/supress a emotion, that emotion doesn't go away - it will still affect your behaviour, tough often not in the manner it would if not supressed.
Again, i will take myself as an example. I subconciously avoided acting female all my life and "acted" male. Any observant person noticed that i didn't do so very well - my behaviour was akward, felt slightly detached and was over the top every now and then. That's typical for an emotional release for a supressed emotion - someone who supressed the emotions about the death of a loved one will also act akward etc. in situations where this will matter.
All the supression means is that you do no longer conciously deal with that emotion - someone who supressed the death of a loved one will likey think that he dealt with it long ago, when he in fact didn't.
There is plenty of reason for such a supression with transsexual people. After all, everyone is telling you that you are a boy/girl, even if those people would be accepting of your transsexuality - they just don't know any better. There is simply enormous social pressure applied - and some people are just naturally good at lying to themselves.
Oh, and while we don't have a sure way yet, looking at the BSTc and INAH3 after death is already giving a good idea whether a dead person was transsexual or not.
So it seems that we mostly agree but where we do disagree is a nature vs nurture type of thing. That is fair I think since it depends largely on interpretation of current data and waiting for more research to give us more data.
Sorry, but see above.
We simply have not found even hints for any social mechanism causing transsexuality or gender identity. We don't even have a good idea for possible causes, much less concrete data or explanations - almost everything has been ruled out already.
On the other hand, there are some clear differences in someones brain that are at least very strongly correlated to that persons gender identity. That's not necessarily the direct mechanism for gender identity, but it's a good lead and (other than the social theory) we have not ruled out that many possiblities here.
So it does not, in fact, "depend on the interpretation of the current data". Because the data is quite clearly ruling out a lot of social causes, while there are still a lot of possible biological causes.