Comment by tsoukase

Whatever relates to DNA in an organism is under strict control and huge protective mechanisms. For example DNA replication has an error rate of 1/10^9. Obviously, selecting 1 out of 10-150 million "persons" is some fierce form of survival of the fittest, that happens early and is very cheap. The next layer of selection is embryonic development, next the labor and in the end early life diseases. At every level the selection becomes weaker but the price larger.

We are some pretty special and die-hard persons.