Why do people act like pigs?

My father is such a pig he eats like one looks like one, he's real fat like me but I have manners unlike my father when he eats he smaks and talks when food is still in his mouth he snorts like a pig when he chews and and when he burps and do things like that he never says excuse me, sometimes I wish he was gone its that bad. I told him it's disgusting but then my mom gets mad because I hurt his feelings my mom has real good manners so I have know idea wear he got his. Anyone els in this kind of Situation