I reckon being trans is the disorder, they don't feel right in their bodies and need change.
The gender roles tied to biological sex have been mostly the same for thousands of years (of course there are exceptions or variations), this modern reversal and mixture of roles has been more of a social construct than any previous gender roles, nowadays you can see the gears turning.
As for bathrooms and stuff like sports, scouts and other differentiated avenues the rule should be biological sex. Bathrooms could even be labeled XX/XY.
The gender roles tied to biological sex have been mostly the same for thousands of years (of course there are exceptions or variations), this modern reversal and mixture of roles has been more of a social construct than any previous gender roles, nowadays you can see the gears turning.
As for bathrooms and stuff like sports, scouts and other differentiated avenues the rule should be biological sex. Bathrooms could even be labeled XX/XY.