Oh don't worry. I know all about this.
Every single one of my students gets away with murder because of some effing doctor writing a note excusing little Johnny for smashing little Suzie in the face with a textbook.
In all honesty, I haven't given it enough thought to agree or disagree with him. At times I agree, I think we are all a little fucked in the head, me included. At other times, I think some of us are perfectly sane, normal, whatever and it's only a small handful of the population that is that way. Not saying that all instances of whatever they diagnose is "bad parenting or bad behavior" b/c I don't think they all are. Each person is different. Sometimes no matter how much you reinforce a postive, they will still do the negative. Why? I haven't a clue. Could be b/c my friend is right, it could be as simple as some people are just screwed and have some wires crossed.