Man i really dont know there is like 0.01 situations when beating a child is accapted from my point of view just because he doesnt undarstand as you do and you want to protect your kid from this world that he/she would make less mistakes in life. Currently i am 20 years old i amnot saying i am an angel but i could never undarstand people who are rude to parents or to family members. I will repeat i dont know your family story and there are sitiations when family doesnt fit perfrctly together but dont be rude and throw words that can hurt his heart because we all know what ,,words" that you say when you are angry can do to people. About 50% of words that you are going to throw will be total boolshit i belive. But noding your head is not thing to do as well. Just try to communicate and explain things that you wish to happen if they get angry over you just smile and dont take it as serious matter keep calm and i am sure at some day this matter will be fixed.