I don't see it that way for either... you either are or you aren't a mom/dad/mother/father... but I've never called anyone mom or dad or mother or father who wasn't biologically my parnets. I never saw the point or reason for it and and have always thought you just deal with what you got.
Yeah that always pissed dh off because bm would/does with hold ss from dh and then tell everyone with ears that dh just doesn't care to bother with ss. She still does this even though ss is here weekly. She completely denies it to people. There's plenty of women who that would fit also but its rare you see that and honestly I think its because women are more snippy to do/say things like that. Dh would have been able to say that about my adopted sons bm because she did give birth but that was it. He never did. Its just not like him to do/say things like that. But I'm sure its also because its way more well known of dads who walk away from their kids. Its like the saying "Theres two sides to ANY story and somewhere in the middle lays the truth"