I was smacked as a child, and occasionally hit with implements (hair brush etc) and physically pushed around and threatened as a teenager by a stepfather. I can say it harmed me.

DH and I used to smack on a fairly rare occassion... until the day our DD ran out the front and stood on the nature strip and yelled "You're going to smack me!!!!!" over and over again... very embarrassing.... but on reflection i say "good on her"!

So we don't smack anymore. I think it's even more important we don't use physical violence with our boys as they can be more prone to using that as the main strategy with others.

actually... to clarify: I have smacked my toddlers hand away when he has reached for hot coffee or pulled my hair really hard or deliberately broken a few things. So I haven't totally stopped... but I am almost there