I found chapter 10's conclusions about single parent families to be very surprising; especially those about single mothers whose husbands had died. According to the book, children raised by single mothers whose spouses passed away exhibit no abnormal emotional or behavioral problems compared to children in traditional, two-parent households.
Just because a child doesn't show problems doesn't mean they're not there. I know from personal experience; my father fell terminally ill with melanoma when I was nine, and passed away in 2005, when I was 12. My mother has not remarried.
I was very close to my dad, and i took his death very hard- when I think about it, though, it didn't really have negative effects on my behavior. He was the authority in my family- he laid down the law. Even after his passing, the idea of disobeying him would scare me. I had my disrespectful streak in high school- what teenager didn't? My Junior year, after an argument during which i had yelled and swore at my mom, she asked me, "Do you think this is okay? What would your dad say about how you treat me, if he were here right now?" I had a pretty good idea of what he would say- just thinking about it made my gut clench up and gave me chills.
The point I'm getting at is maybe losing a parent in a family doesn't cause behavioral problems, but there's an emotional impact that shouldn't be overlooked.