>>1602114I think you're mixing up gender with gender roles.
The idea that men should be tough and hide their emotions, that women should be submissive and do makeup and everything while men who wear womens clothes or do makeup are called faggots is indeed a societal construct. There's nothing about my XY chromosomes that dictates I cannot wear a bikini, I'd just get a lot of weird looks if I walked out on the beach with one on. But if every guy wore a bikini to the beach we'd think nothing of it.
Trans people don't feel like they belong to a gender role so much as a gender, I guess? I like having a beard and my dick is pretty cool, I cannot imagine wanting to cut my penis off or wanting to grow a pair of tits or laser off facial hair, but that's what the trans girls do voluntarily. Even if I got drunk one night and thought "hey that sounds interesting", I wouldn't want to do it after I sobered up.
I don't see any reason to doubt that they are born like this.