Response from @sokale:

I know now that I feel more out of place as a human rather than as a female That was more or less my conclusion after my own teenage gender dysphoria in the mid 2000s, you're not alone. I think the underlying 'cause' is that the social constructs around gender, if they're not something you just automatically internalize as a part of your socialization, are not easy to wrap your head around or fully identify with. Autism makes it difficult to automatically internalize any sort of socialized behavioral expectations, let alone one as nuanced as gender, which is treated as such an obvious thing that it warrants no explanation in the public mind. So those first seriously encountering gender consciously as an adolescent, already struggling with understanding and engaging with all the other aspects of culture which are expected to come automatically, are going to be less readily able to integrate themselves within those constructs for the simple reason that those constructs aren't designed to be consciously integrated.

I do tend to think that a lot of how non-autistics identify with gender sort of starts as play-pretend and mirroring certain popular archetypes, and then eventually those neural pathways solidify and it becomes more second-nature, though I doubt a significant proportion of humanity have ever fully identified with every aspect of their designated gender and this is the reason for much angst (feeling one isn't a 'real man' or what have you). A sort of narrow conception of being "cis" seems especially unhelpful when really most people have always varied in the degree to which they identify with such roles and fulfill those social expectations, and in modern times these social expectations have already become so much less strongly enforced. How I look/dress/speak and what interests I have aren't defined by my gender and I don't see why those things should be connected in the first place - I'd never identify as anything other than a man simply because I don't think "man" means all that much on its own anyway, it's as good as any other label and colloquially the most useful in my experience. Anecdotally, growing up, 'gender' wasn't at all a topic of conversation. Later in my teen years it had just started being one, but early on I'd sit through Sex Ed or hear about development and think "Oh, I'm probably an alien", or I thought I was secretly Downs, or piloting a meat-suit mecha cut off from the realm of normal humans whose ways I would never be a part of. It's really taken a long time to get beyond that sort of thinking.