Hot Tempered Child

I would like to ask your advice on how to raise a boy (4) who comes from a family of hot tempered and impatient people. He emulates everything he sees and is easily distracted. However he is a quick learner! My concern is…he is already being a bully towards his mum and grandmother and has a bad temper. A lot of his behaviour is his environment at home I know this. I realise that raising a child is not only nature but how we nurture them but then how can I teach an “old dog new tricks?” with my family including me? I would like for him to approach life with peace and calm….