Carlyn -- I agree with you that the type of BEHAVIOR that Colin describes is gender-inclusive.

The problem is when people leverage their genitalia per se as the de facto JUSTIFICATION for why they should be the recipient of special treatment. Obviously, this is a heteronormative trend. As you pointed out, it can work in either direction (men toward women, or women toward men).

When it's people of the same sex trying to take advantage of one another, it usually isn't predicated on some outdated notion of "chivalry" or the possibility of romance. Very few gay male or lesbian couples are going to experience one partner saying to the other, "You should do X, Y, and Z for me -- BECAUSE OF your sex/gender per se."