Boundless energy.

Until you have two children it is hard to fathom that they could be so different. Our older son is pretty mellow and laid back. You won't find him running around like a wild man. Our littlest son on the other hand worries me daily. I often wonder if I need to shop for affordable term life insurance for him. If there is a way to get into trouble the child will find it. In reality he is just curious in an entirely different way from his brother. The little guy just has to get his hands in or on something in order to understand it. His older brother on the other hand learns from researching or observing the world around him. I love this difference in them but I can already tell who is going to keep me awake worrying for years to come.