I smacked both of my sons (smacked, not beat-up, and only when all else failed).
One studied hard at school, got good grades, loves and respects his mum and me, has a lovely partner, got a good well-paid job and is now the manager of a fairly large store in a very swish area in Yorks.
The other one pratted around at school, flunked his exams, is a heroin addict and doesn't seem to care much about his parents one way or the other.
Conclusion - being smacked either:-
1) Had opposite effects on the two of them, or
2) Makes no difference, either good or bad.
So which one is it? I find it strange that so many people are so absolute in their opinions - "Smacking's always wrong", or "There's nothing wrong with a good slap" - on a subject which has no absolutes, no 100% correct answers.
Like the "Which is the best guitar" question, it's up to the individual to decide, there's no such thing as absolutely right, or absolutely wrong. IMHO! :-)