Hmmm.
I have read this thread for some time now and can see where Bronto and others are coming from. I defer from taking any sides as it is a highly complex issue, which I will attempt to outline below for those who have the patience with my scientific musings and research.
I understand what Bronto is trying to explain, and it makes logically sense. If a person is physiologically male and feels female or has the desire to be female, that can indeed be considered a fault of the mind to align with the biological manifestation.
And this may be the issue for those who have grown up with highly confusing nurturing stimuli that would somehow mess up their gender identity. Trauma would potentially contribute significantly.
I also understand that Bronto and others are not attempting to judge mental illness as anything other than a state of mind which differs from the norm. Current attitudes are now changing regarding mental illness, which means it is becoming easier to accept that one may not be aligning with the norm, but that it is okay and there are means to deal with it in ways that do not alienate the individual further, but seeks to understand and thus integrate.
However, there are individuals that have a severe discrepancy between the perceived mind/body divide. These individuals struggle to the point where it only feels right to alter the body to align with the mind, rather than the other way around.
There are very distinct physiological/anatomical differences between the male and female brain. I hope what I am presenting here would give some incentive to reflect on the potentially profound effect even small physiological differences in the brain can make, regardless of sex.
Fairly recent studies have revealed a consistent and very distinct shift to female brain anatomy of androphilic male-to-female transsexuals. These results were conducted on individuals who had no prior hormone treatment. Using fmrI, there was a very clear response to sexual stimuli in the biological males that was not present in biological females, and the androphilic transsexuals shifted towards the female response patterns.
Source
Secondly, and this is where it gets very interesting is where actual mapping of brain anatomy
reveals white matter microstructure in male-to-female transsexuals to fall halfway between that of biological male and female controls. This would indicate a potential 'failure' to develop full masculinization during brain development.
Conversely, in gynephilic male-to-female transsexuals there was no indication of feminization of the brain structure, and that gender dysphoria may be associated with changes in multiple structures and involve more complex network interactions. Gynephilic transsexuals "
displayed also singular features and differed from both control groups by having reduced thalamus and putamen volumes and elevated GM volumes in the right insular and inferior frontal cortex and an area covering the right angular gyrus."
Thus:
Contrary to the primary hypothesis, no sex-atypical features with signs of 'feminization' were detected in the transsexual group....The present study does not support the dogma that [male-to-female transsexuals] have atypical sex dimorphism in the brain but confirms the previously reported sex differences. The observed differences between MtF-TR and controls raise the question as to whether gender dysphoria may be associated with changes in multiple structures and involve a network (rather than a single nodal area).
This suggests there are specific brain structures associated with gender/sex confusion in male-to-female gynophilic transsexuals, however these do not affect sexual disposition.
Several studies were conducted over the years in mixed samples of male-to-female transsexuals, but the results have been conflicting where some demonstrated differences and others none.
In 2009, however, a
UCLA study of mixed male-to-female androphilic and gynophilic transsexuals reported the following: "
However, MTF transsexuals show a significantly larger volume of regional gray matter in the right putamen compared to men. These findings provide new evidence that transsexualism is associated with distinct cerebral pattern, which supports the assumption that brain anatomy plays a role in gender identity."
Gynephilic female-to-male transsexuals show
distinct male-like neuroanatomy, even before the test subjects started hormone treatment.
An example of the powerful biological imperative is evident in the case of twins Bruce and Brian, born in 1965 in the USA. As the boys had trouble urinating, it was recommended that they be circumcised at 6 months of age. Bruce's penis became permanently damaged as a result and after many consultations it was decided that Bruce's penis had to be removed.
At the time a psychologist was promoting the idea that gender identity was completely a matter of nurture, and thus the parents decided in consultation with the experts at the time to raise Bruce as a girl and not let him know his true gender after the castration. He was renamed Brenda.
Brenda resisted from day one, and eventually became unmanageable. Her rejection of her female identity continued through to middle school and got to the point where she was bullied and harassed by other females. She wanted badly to be a boy, and even attempted to stand up while urinating, like a boy. The problems became so severe that the parents were eventually given the advice to construct a vagina for Brenda, so that she could fully accept her femininity. She rebelled completely at the prospect and attempted suicide several times over the coming years.
At 14, the parents were desperate and so followed the advice from a local psychiatrist, and decided to divulge Brenda her true gender.
She immediately accepted it, cut her hair and renamed herself David. David went through a series of body alterations such as double mastectomies (she had received hormone treatments to promote growth of breasts) and the construction of a penis.
As David was now able to express his true male identity he was accepted by other boys and started behaving like other teenage boys and even began dating young women. He married and had a successful relationship with his wife for some years.
David suffered from chronic depression, however, and committed suicide in 2004.
Source
As this case is a single example, it does not provide significant evidence for the nature vs nurture argument one way or the other. This is because the gender-reassignment did not start until he was 2 years of age, and is thus not enough to reject the nurture argument. It is hypothesised that the first two years may be sufficient to establish a gender identity through nurture, but the question remains unanswered as this is very limited evidence.
Many recent studies provide some interesting evidence in support of the nature theory, however, including the studies cited previously. These are but a snippet of the available evidence out there, so if anyone wants to investigate further there is a plethora of literature, although some not available to the public.
Now, I'm a trained scientist (disclaimer: I am not a neuroscientist, but I have background in biology, anatomy, physiology and many other scientific disciplines), so I know better than to jump to conclusions, just because the evidence seems in favour of a certain trend currently. The field of neurology is quickly evolving with better technological developments, and I think that we in the near future will be able to gain better insight and understanding by looking at the physiological and neurological and how it interacts with the psyche.
However, if it is indeed the case that anatomy, and thus the biological imperative has such a powerful influence over the psychological, we have to review how we assess mental illnesses in the future. Further research is needed to investigate physiological/anatomical/psychological interactions.
Yes, these individuals are perhaps mentally ill (aren't we all to some extent). But perhaps for reasons that are hidden in the biological imperative - the part of the picture that remains hidden for now. If one is indeed hard-wired in the brain as female, but have a male physique, the conflict would be inevitable as society and culture has expectations based predominantly on the physical. The result would certainly set that individual up for psychological challenges.
I hope this can give some cause for reflection, for those who are interested.
So much in our society depends on knowing someone's birth gender. If you make it legal for anyone to change the gender on their government-issued ID based on how they mentally feel, there's going to be chaos. It's one thing to allow people to change their names. Gender is an entirely different issue. States will not allow someone to change their birth certificate gender unless the individual undergoes sex reassignment surgery or some kind of physical "gender transition." 
I will interpret a lot of words a bit different then a native speaker. When unsure I must look them up. So it is not a 'natural' language for me. So maybe related to the thread in a way. Am I passable? I took the comment about 'part of the English speaking word' as a compliment 
*cautiously puts a foot into this thread* *looks to see if the coast is clear**Do I really dare get into this mess?* 
