When I move one hand, the other moves the same way?

All my life my hands have slightly mimicked the actions of the other hand. If i wiggle the fingers on my left hand for example, the fingers on my right hand will uncontrollably wiggle a little bit. Ive also noticed that when I brush my teeth or lift something like a milk jug, my free hand is always clenched in a tight fist. I was just wondering if anyone had this same strange problem?