Why wasn't the backstpory explained? re: mom and brother's mental family

When the brother was asking her is she was OK, and if she talked with a shrink, she said she had 17 years of shrinks and they did her no good. That was the 1st indication that she has a history of mental problem, going back to her teen years, so beyond her PPD with Joshua. Then, when she was hospitalized, the brother was apologizing for not going into the hospital because of the smell. He then says something to the dad about having experience from his family.

I thought the movie would shed some light on what kind of mental problems run in the family, that would maybe explain Joshua a little better.

Anyone else feel like this should have been explained better?