Brain Damage?

Do all kids have brain damage? Or is it just mine? Don't get me wrong- there are no flies on Ty, and I think he's smart as a whip... But good grief! Just the other day, he took a car and threw it at his little friend. Whe I asked him why he did it, he looked at me so sweetly and said "I don't know." Yesterday he took apart my vacuum cleaner. When asked why, he replied "I don't know". And this morning- I had given him some Tylenol and was washing off the syringe at the sink. When I turned around, he had taken the bottle of Tylenol off the counter and was attempting to swig the rest. I took it from him and asked why he did it... he told me "I don't know." I know this one could have been partially my fault- but I thought I had put the bottle far enough away from the edge of the counter... but I swear sometimes those little arms just grow and grow. They may only look a few inches long- but in actuality they must be 8 feet or something. So what is it then? Does he really not know why he threw a car? Does he really not know to take things I told him to leave alone? Is it really brain damage? I really want to get irritated at him for it all- but let's face it... he was kind of cute covered in dust from the vacuum... and he looked so guilty with a bottle of Tylenol in his hand... I knew I couldn't laugh because all the books say that just encourages the behavior- but you would have to have a heart of stone not to be able to smile a little.