Strange inherited behaviors

I have a friend whose two sons area couple of year apart had the same quirky behavior when they were babies. With elbows down the side and hands extended from the body, they flipped their wrists with loosely closed fists.

My boys are nearly three years apart, and the oldest one used to have this habit of grabbing a cloth or sheet between his ring- and middle fingers moving gently back and forth, so that the cloth would touch the skin between the fingers. Then, the other night I put the younger one to rest, and to my amazement he started doing the same thing. It appears to be of some comfort to them.

In both cases I am confident that the younger brothers did not imitate the older ones, as they had ceased the behavior when the younger ones began it. I am left with the surprising conclusion that such behaviors are inherited. Unfortunately, I cannot say whether any of the parents did the same thing when they were children.

I found it strange that such behavior should be encoded in our DNA. If anyone else has observed similar behaviors in their children that they trust are not learned, I would be very interested in knowing about it. Alternatively, if you know of anything that you did as a child that you have observed in your own child, that would support the same conclusion.

<sarcasm>Since most visitors here so diligently leave comments every day, I though it would be great if you shared your own observations of inherited behavior with the rest of us.</sarcasm>