@SlothSlothSloth
'Such people have always, always existed.'
Exactly how long we have had transsexual people with us is not clear to me.
I am sure you know ooor Lili Elbe, died from an operation in 1931.
Christine Jorgensen had a different (successful) operation, she was not the first but waa back in 1951 and so actually 'sexually' transitioning doesn't date back a long time. Prior to this might men have appeared as women to date other men, were they trans gender or maybe just gay, and likewise might women have appeared as men to date women?
I don't think every women who pretended to be a man to get a job or avoid a man was necessarily what we would now know as trans gender.
But if you have evidence of a long trans history of course I am open to reading it. 
'Whether or not we think it’s right that they have to change themselves in this way to be happy is neither here nor there'
Of course people must do what is right and legal for them. I've not seen many people complaining about this (if any). Only really when it is children who are too young, legally, to make this decision.
'..these people clearly exist and transition does help them.'
No disagreement from me.
Another group of people also exist, those who are not dysphoric and making demands on women and their spaces. I think you will find many women, including many feminists were not distressed about being in company with trans women.
It is the TRAs that are the problem.
And I really doubt anyone really thinks the massive numbers of young girls wanting to become 'boys is a naturally occurring phenomenon (I am saying that in a totally neutral way, if you know what I mean) in the way that a very small number of adult men or women expressing a desire to transition is.
'I don’t believe in brains in the wrong body.' - I agree.
'I don’t believe many of the current wave of trans people, especially the teens, are genuinely trans.' - I agree.
'Genuinely trans, to me, means genuinely dysphoric in a way that only transition can address.' - I agree,
Wow, when we agree we really agree. 