My stepdad once hit me, because I didnt get off the pc when he told me to, so he hit me then ran up the stairs after me. I was 17 at the time, and near the top of the stairs, I stopped, turned round and slapped him round the face!
I then got in s*** for it because I shouldnt of hit him because he was diabetic!
He had hit me before, just before I turned 16, and I ran away, only for a week mind you, but probably not the best solution!
But I do know, that even now, if it happened again, I wouldnt hesitate to hit someone back if they hit me in that situation!
Believe it or not, Im now closer to my stepdad then I have ever been and love him to pieces!