What do "gender roles" have to do with expectations of marriage and family?

Thank you for your question.  
 
However, I believe that to answer it well, your question will require
more time and effort than the average amount of time and effort
associated with this price. Here is a link to guidelines about pricing
your question, in the pricing guide:
https://answers.google.com/answers/pricing.html

A simple answer is that men and women are each expected to do
different things.  Many gender roles are stereotypes, but that does
not keep them from being true.

For example, the woman is expected to take care of the kids and home,
and the man is the breadwinner

Read Justin's comment.  Nice and simple.