In the state of California divorced parents have joint custody of their children, having "overnights" at both residences. Therefore children have two separate bedrooms, one at mom's and the other at dad's. Additionally, they usually have a third bedroom at their grandparent's.
What does that mean to real estate developers? Firstly, it means more housing units (one for mom and one for dad), and that every housing unit must have a minimum of two bedrooms. In the past when moms won full custody they had a two bedroom unit, and the fathers had the kids for only four days per month (every other weekend) and so they lived in a one bedroom unit and the kids slept on a pull-out couch in the living room. Now that fathers have joint custody they have to provide a bedroom for their kids.