I am 33 years old and my hands have done the same thing since I was born. I dont know what it is, I have been told that both halves of my brain are too close together!? I don't believe that I have any learning disorders or any other problem from this. I can type 60 wpm (practice) I can do everything like everyone else.
I would love to hear more about this condition (if that is what you would call it), it would be nice to at least put a name to it. I can tell you it is refreshing to see that I am not the only one going through this.
Don't worry about your children and this problem, it's so minor they are fine, I hope this helps ease your mind a little.