He may just be an early developer . Don't worry too much. They start to tantrum when they want to distinguish themselves as a separate person to you. It is very healthy. Our DS had tantrums from this age. The best thing you can do is to set clear but reasonable rules with logical follow through if he tends to push the boundaries. Don't have too many rules (make everything as toddler proof as possible) and offer comfort when he works himself up into a tantrum. He is just expressing that overwhelming feeling of powerlessness when he doesn't get his own way. He will learn to deal with those feelings as he gets older but it helps knowing that you still love him even if he can't get what he wants at the time (eg. the 10th bikkie, climb the curtains, pull the cats tail. lol). And cuddles or you just being near helps him to learn that he will recover from disappointments. I think for sure it must be harder for the younger ones to see their older siblings being allowed to do something and not understanding why they can't.
Oh the joys of toddlers hey?