Is it possible that a child can have adhd at 4? the father and i both had it as children. this ha been going on for a year and half. he's on the go 6a-11pm. aggressive, screaming, can't sit still, doesn't follow rules, demanding, hits and punches

Yes: His pediatrician should be able to make further make recommendations, his symptoms are suggestive of a condition from the attention deficit spectrum. Other conditions are still possible and it will be important to be properly ruled in or out.

Yes...but...: I would look into having the kid evaluated by a child behavioral specialist. These include some child psychiatrist/psychologists or professional counselors with special training. S/he may or may not be candidates for medication or other forms of behavioral therapy.