Rav Avigdor Miller on Hitting Big Boys and Little Girls
Q:
The gemara says that a father shouldn’t hit a son that is older. What age is that?
A:
It’s forbidden to hit a grown son because you might cause him to hit back, and that would be a big sin that you brought about. Or it could be you might cause him to do something else. At what age does this prohibition apply? It depends. It depends on the style, the culture of the day. It depends on the country where you live. If you can bring up your children to accept parental authority, then it can continue for some time; and the fact is you wouldn’t have to use any chastisement after a certain age because big children already respond to other forms of mussar. But exactly when you must stop chastising children, that’s something you’ll have to play by ear.
TAPE # 356

Q:
Is it proper for a father to hit girls as well as boys?
A:
Certainly! Girls need instruction and although in many cases they don’t require as much treatment as boys, but certainly a slap once in a while is a medicine for girls. Now, this I have on good authority. There was a man who was on the administration of a girls’ seminary and he said to me that girls have to be chastised too; it’s important to chastise girls. And he said to me, anybody who punishes a girl is doing a favor to her future chosson.