2 year old with behavioural issues!?

Basically, my 2 year old nephew (still young i know) is extremely destructive! He literally does not stop going from the minute he wakes up, rampaging around throwing things, breaking things, hitting things, screaming, everything. He is also quite violent towards his 3 and 1/2 year old sister, kicking, slapping, biting, headbutting! He does not listen to anything you say, and there is no such thing as sitting down with him on your lap- he is constantly going. He does not do these things in an angry or upset way but he seems to find it funny and a sort of game. I'm becoming worried because there is a history of asbergers syndrome within the family... he also doesnt seem to have any concept of commands- if you say "frankie will you get me the ball please over there" he doesnt even look to where you are pointing. Is it a bit too early to worry about these things? is it abnormal and should we take him to a doctor...any help or personal experience gladly appreciated