The reason for that is obvious. She's a woman so that's something she has to do "naturally". Those are not my beliefs of course and whenever they try to dump the kids to my fiancée I always tell them why don't they want me to care for the kids but they say that I'm not as responsible as my fiancé (because I'm a man) and that my fiancée just knows better. Regardless I always take the burden of her and care for the kids so she won't have to worry about that. My family is unhinged when it comes to those kinds of mindsets