This is less because of expectations within that group as it is with members of that group reacting to things which personally impact them.
Again, sure, but you are expected to adhere to group expectations and "proper" identity politics if you are assigned to a minority grouping based on a trait. You would recognize this if you'd ever been a right wing black person, anti-feminist woman, or anti-affirmative action "coloured person", etc. As I wrote above, you are expected to speak, vote, think, and act the way your assigned group identity does.
"Cultural Appropriation" accusations, "Acting White" accusations, etc also tend to rear their ugly heads in this arena.
Either that or people's own rational self-interest factors into their decision making somehow.