Are complex gestures gentic or learned behaviors?

[noblebaron]

I've been a step-dad of a step-daughter for two years now and have really enjoyed getting to know her and settling into my role as a new dad.

My daughter's birth-father was a roommate and a very good friend of mine for about five or six years. Life worked out strangely... and I am now his ex's fiance and a father for his natural daughter who is now nine years old.

She hasn't seen him since she was a few months old, and only for a few minutes at a time even then. She has never been in contact with any of his relatives.

Here's my question. How is it that she sometimes does a number of gestures and facial expressions EXACTLY as her birth father did?

When she does these expressions, my fiancee and I often look at each other and crack up because we are both thinking the same thing... that was JUST like (his name)!!

One of these gestures is tucking her right elbow into her side, flipping her hand over, leaning back slightly and laughing with one side of her mouth upturned in a very specific way. You would think that would be a learned behaviour. Could it be genetics, plain and simple?

What gives??

Thanks,

-NobleBaron