We went to my mums house for dinner today, My children were having great fun with their cousins, the two 6 years olds can get very hyper and a bit cheeky when together, they were playing in the office along with my 2 year old and 8 year old when my father went to the loo he didn’t close the door and the two 6 year old were annoying him and shouting at him silly things, he came out of toilet and shouted at the 4 of them and slapped my 2 year old on head and banged the door shut, I heard the bang and ran from kitchen to see what had happened, 2 year old roaring and 8 year old very upset as had never seen grandad like that, she said he hit two year old on head, my dad just left and said he only tapped him, two old very upset holding head, I was upset so just left and went home... my father is 70 and probably not able for the hyperactivity of them but this was unacceptable and I’m very upset but don’t know how to approach it, he has never done this before to grankids but was a tough father at times when we were growing up but has mellowed alot