This is an interesting topic.
I have noticed that households with 2 parents have children that attend college and at the very least become solid professionals, while children raised in single family homes have more of a tendancy to skip college and struggle.
That is at least what I've seen amoung my friends. There are of course MANY exceptions to this rule, but this is what I have seen personally.
So I believe the 2 parent thing holds some importance. I'm not convinced that a single parent has enough power to control their children, especially come teen years, at least in America where laws protect children.
I know for a fact there was not alot my mother could do to discipline myself of my little brother. If we wanted to do something, we would, there was little she could do about it. She was too busy trying to pay the bills to have time to devote to us, not her fault at all, she just needed help.
Every family has issues, every child is gonna carry some issues with them from their family, but the only constant I've noticed is that single parent children have done poorly compared to 2 parent households.