Pushing and snatching

Hong Zheng has a very bad attitude which really worry me. He likes to push his cousin who is 6 months younger than him. He also like to snatch away his food. How am i going to teach him on this? At first i only keep telling him his cousin is still a baby and you cannot do that but it did not work. Sometimes i will hit and yell at him immediately when he repeat the mistake but he just does not change. I observe this since two months ago and there is no sign of understanding from him. How am i going to do?