This is very funny! We have this in our family as well. My father did it, possibly my grandpa, my son does it, my nephew does it, etc. It must be genetic. We are all super tall, my dad, 6’5, myself 5’10” flats/barefoot, I am always wearing some sort of heel. I was always told it was genetic and is a sign of intelligence or higher brain function…I will continue my search as to why my son does this. I find it cute since he is not actually impaired muscularly or mentally. BTW…the girls in our family have a normal gait. odd.