I'm speaking from some experience. Failing to be feminine correctly used to freak me out.
Just as an example: like most humans I have hairs on my chin, discovering these hairs as a teen filled me with fear and revulsion that had little to do with anything rational. That was because I'd experienced the way that kids could isolate and jeer at someone who didn't do gender correctly.
And I had no idea what might trigger that kind of bullying and ostracization. 2/