Is it that marriage itself is beneficial or that people capable of maintaining a relationship make better parents? Divorce is significantly more common for bipolar, paranoid, and schizophrenic people for example. So I think we need to look at widows or something to control for those kinds of issues.
>In the book, released last month, Kearney points out a rather obvious fact: Children raised by two parents have a much higher chance of success than those raised by one. Yet she goes even further to argue that whether parents are married or not impacts their children's success.