Our 21 month old son is a very happy toddler. He is always laughing and enjoying life unless he wants something which then he continues to screech at the top of his lungs. He was always ahead in development until he was suppose to start talking which isn't happening. But I understand that this can be normal. The thing is he is also very very energetic.

He is so energetic to the point that when I bought him some flashcards to try to work on his words (still doesn't speak) he simply shoves them all off the table or will try to take them and throw them everywhere. He will look at his books himself in a calm manner but he is very much into destroying things. I.e. when we try to play duplo legos with him he immediates knocks down anything we try to build then will sweep his whole arm across the table until every last block is on the ground. Sometimes he will even begin kicking them.

I have seen this behavior and lack of focus from my younger siblings and it worries me because they have ADD and ADHD and my younger brother also has functioning autism. And compared to that my nephew who just turned two in december is drastically different. He is calm and listens, he seems to enjoy learning and he speaking in phrases already. On the other hand he also doesn't seem to be as happy or full of life.

I love everything about our son, from his constant dancing everytime he hears a beat to his energy that has his running from one end the house to the other 40 times in a row. Its just his lack of listening and his open defiance and his unwillingness to calm down long enough to learn that has me worried for him. Can this behavior be normal or is it early signs of other problems?