Oh, this you thought of being theoretic skeptical of your genetics! But what i think in my view that my reasoning is simple logical that god the higher authority gave imparted us our genes and differentiated us into various races! And we as individual identities are just as same as people had been on earth in time period 600 a.d.! Only that the people races before were somewhat different and through the ages just some glimpses or way of seeing changed! Or moreover races were dispersed into each other biological surroundings!