I suspect that parents of rebellious children feel guilt for a variety of reasons. It's only natural for a parent to wonder where he or she went "wrong." We all do that (because all kids rebel at one time or another), and it's only natural to do some soul-searching.

Another reason for guilt is that other people make us feel guilty by gossip and unkind remarks. And then there's the guilt that comes from worry--worrying about our children, especially when they are no longer under our influence.