Nature or Nurture?

With classes done for the day, I'm walking out towards my car and went to grab my keys.  I'll share my thoughts with you, "Hm.  Not in my pocket.  Isn't that where I normally put them?  Better check the other pocket.  Hm.  Not there either.  Drat!  Now I'm going to have to dig through my bag to find them.  That can wait till I get out to the car."  While my mind drifts to other thoughts, I look down and realize my keys are in my hand with my water bottle.

Have I observed enough times my mother looking for her glasses while they're on top of her head that I learned this skill?

Or is it just passed down in my DNA to get things done without realizing it?  (Isn't that a nice way to phrase it?)