Here's my reply to Gia Milinovich's second recent blog entry tiptoeing around the delicate subject of trans rights and whether we should be allowed to have any. Note that her blog entries themselves don't explicitly state this, but if you read her various discussions with people on Twitter at the time, her motivation and true feelings on this subject become clear. This reply of mine is still awaiting moderation on the blog entry's page 24 hours after posting it, so lest it be lost forever, here it is:
First of all, let's ensure we're not arguing semantics. I don't think anybody is arguing the point that gender roles are arbitrary social constructs. Gender identity, however, is essentially your neurological body map telling you which sexual characteristics your body should have. I realise that it's difficult to notice you have a body map when it happens to be aligned with your body. It's the kind of thing you only notice when there's something wrong, a mismatch between what your brain's set up to receive stimulus from and what's actually there. But that doesn't stop you from having a body map, just because you don't notice it. Similarly, if your clothes fit, you probably won't spent much of the day thinking about the fact you're wearing them, but that doesn't mean you're naked just because you don't constantly notice them.
So with the semantics out of the way, we merely have to look at the brains of transsexuals to see that they're sane and telling the truth about who they are: transsexual women are women, and transsexual men are men. With the parts of the brain that are on average sexually dimorphic (the same way height is on average sexually dimorphic, and if you looked at the average height of a group of women and a group of men, you could tell which was which, even though for any given person you couldn't tell their gender based on their height), you can look at groups of women, both cis and trans, and groups of men, both cis and trans, and see that on average trans women and cis women are more alike than not, and trans men and cis men are more alike than not, and that while there's substantial overlap between women and men, they do tend to correlate around different measurable values.
While this area of neurology is still in its infancy and requires a lot more experimentation, data and studying, we're already getting to the point where there's no controversy about this, among experts in the field. I'd suggest we listen to them, rather than speculate amongst ourselves.
Here's what Robert Sapolsky has to say on the matter of transsexual brains: http://www.youtube.com/watch?v=LOY3QH_jOtE#t=1h23m52s
This is what Margaret M. McCarthy says about the sexual dimorphism of brains generally: http://www.youtube.com/watch?v=uk0M154oM4c
Here's Veronica Drantz giving a presentation on the myth of the gender binary: http://www.youtube.com/watch?v=M1oVv59o-UQ
If you'd rather go straight to the source and read the actual white papers, I'd recommend those curated by Zoë Brain, above: http://aebrain.blogspot.com.au/p/transsexual-and-intersex-gender-identity.html Of course, you should read as many as you can if you're interested in the topic, to get a better feel for what's borne out and well replicated versus what seems questionable in terms of methodology and conclusions drawn.
It's always worth bearing in mind that we're talking about things that have very real consequences for real people, when it comes to the rights of already much maligned transsex and intersex people. It's also worth bearing in mind that discovering how the universe actually works is always more interesting than cherry picking what you're looking at in order to achieve confirmation bias. How sex and gender actually work is much more interesting than the kyriarchy or TERFs seem to be willing to see.