this is a kind of silly question for this forum. BUT, Ya'll do realize that every single person on earth with blue eyes is traced back to one person? diversity comes from mutation not from a pre-existing availability of it. In fact the genetic code from just two humans is capable of creating approximately 70 trillion distinct human beings without copies. granted them being siblings will decrease that amount a bit, but not by as much as you would think. And if you think about it technically every single human on earth commits incest, albeit in a very diluted form, any time they reproduce. Because that's just the way evolution works.