"I wouldn't mind so much if someone had had lower half removal/reconstruction surgery, but if they are as born then no, I don't think women-only spaces are for them."
A personal opinion but I don't think that should bother anybody less when you think how messed up someone has to be to voluntarily cut off their own sexual organs. That's disturbed as Hell.
@ReleaseTheDucksOfWar
"Surely there really are some people who are genuinely born into the wrong body though?"
Firstly, great username. Secondly, respectfully I don't really see how someone can be born into the wrong body. Unless you believe strongly in gender stereotypes and that a man like traditionally feminine things somehow makes him a woman, or a young girl who is interested in cars makes her a boy (I pick that example because it's a real case of somebody's 11 year old coming home from school and announcing she "has a boy brain" because of it), then really what makes somebody's brain 'wrong' for their body? Male and female brains aren't particularly different. They develop slightly differently on average but that's because of the environment they are in. For example male brains tend to be slightly larger because male skulls are large. And the brain grows to fit (really!). And they're washed in different quantities of hormones which can affect behaviour and different development of some areas. But these are only general tendencies and if a "trans" person is of a particular sex then their brain has been subjected to the hormones of that sex.
Really there's never been evidence for the wrong brain theory. If there were then you'd be able to test someone to see if they were "trans" or not! But the idea sounds good. It's exactly the sort of pop-sci notion that spreads like wildfire. Nobody has ever explained why some hypothetical tiny physical differences in the brain should determine one's sex whilst a whopping great physical difference like your genitalia should not.
Anyway, you're very far from alone in this being new information to you. The messaging on this was everywhere and counter voices were dismissed as bigots and seldom got coverage except in order to shoot us down.
The idea itself is incredibly appealing to young people who aren't very happy and are dealing with that transition where you go from thinking you're the centre of the universe as a child to realising you are not as you grow up. When I was a teenager I found a book in the school library talking about male vs. female brain. Scientifically disproven now but it was a popular idea. I for a little while thought that I had a brain that was what today would be called non-binary? Why did I think that? Because it made me feel special. If the trans movement had been around back then there's a very chance I'd have been sucked into it. Thank God it wasn't (mostly) and I had a chance to grow out of that idea.
"Hmm. I was thinking that was true then thought that some traits are considered more male than female - eg < dryly> aggression. Sure there are some aggressive females but on the whole the male of the species is more aggressive, and not quite as good at social communication, than the female."
That's a good example of what I'm talking about. A transwoman on male levels of testosterone becomes much more aggressive. A man who through a disorder has depressed testosterone levels, is typically less aggressive. It's a simplification to say that's all it is but it's not the brain being male or female (seriously, even experts wouldn't be able to tell one from the other reliably without DNA testing) but rather then environment it's contained in. Wash it in testosterone, it's going to rev up.
So one could say that a particular brain was more associated with female traits, but then the most important thing would be if the boy - felt- he was female instead of having more-than-usual traits associated with females.
Which brings it back to gender stereotypes as I talked about. Why does he "feel" female? How would he even know what "feeling female" means? Is there actually such a thing as "feeling female" anyway? What he actually means is he doesn't feel he fits male stereotypes and thinks female ones would suit him better.
And this is why trans correlates with autism. An autistic kid will struggle with social interaction. They will feel they don't fit in. They will feel they don't understand other people's behaviour and it doesn't match their own. Along comes the trans movement and says "oh, there's a reason you don't fit in - you're trans. Actually it's because you're special and in the wrong life". But it gets better - not only does it tell you it's not your fault, not only does it celebrate your difficulty in fitting in and provide you a community and posters on the school walls and instantly make you immune to bullying (because schools will crucify a kid if something gets called transphobic). No, not only all of that, but it gives you a manual on how you should behave based on gender stereotypes of the sex you think you are. Everybody knows what "girly" means, so now you know how to behave. Get your nails painted, talk about dresses, etc. You're being girly and you're less socially lost now. Just act like the stereotype of the other sex you have in your head.
"So that would be gender dysphoria."
Maybe. That's more usually, imo, adolescent girls feeling uncomfortable with their body, often uncomfortable with their sexual development or the sudden interest of boys. Sometimes the body image disorder manifests as anorexia. Now it seems like cultural factors are causing the same condition to manifest as gender dysphoria (both anorexia and trans correlate with autism and, imo, with abuse). But just because an anorexic believes she is overweight, it doesn't mean that she is.
Anyway, don't worry about "skating on thin ice". If someone bites your head off for asking a question, that's their problem. I can't imagine anyone here will. :)