uggh, the dialogue for this page gave me such a hassle. so much I even had to get feedback from some helpful guys a TV Tropes.
'How did she know that?' A transgender guy wouldn't say that in response to someone saying they're the opposite of the gender they identify, they would most likely defend their gender identity to the death. You could of had the dialogue be 'Someone said you had a vagina/nothing down there.' with the other character slipping a 'How did she know that?' and gender-variance would've still been a good possibility. The way zhe confirmed assumed femaleness it makes zir identity seem more of a tomboy thing. Someone on tv tropes mislead you hardcore with that dialogue and probably didn't know much about gender-variant people.