We do what we see and what we're told. If we haven't been raised in a family or in a community where women are treated as full human beings and men don't have to be superior anymore, we continue to think that it's not only natural but inevitable.
My mother stopped working when she had my brother. She was a full time mom until I started getting heavily into ice skating lessons, and it got to the point where they really needed my mom to earn an income.