Martin, Hitting a child is basically not right. I have 2 grown up 'kids' 20 & 25, I smacked them both. I regret it, it really didn't achieve anything, it was a glaring sign i had lost control of the given situation and my own self control.
I was brought up smacked, and, like the argument for smacking goes, "it never did me any harm". Well it did actually, it taught me that physically striking a child was OK. The result was me doing it to mine.
It's a lazy way of dealing with your off spring and I reckon it does have latent lasting effects on the kid, even if it means they go into adulthood thinking hitting is ok.
Sorry, It's a load of bollocks to say without striking your child he/she will turn into a feral brat.