Humans have done their best to irradicate natural selection, which is what allowed us to evolve to what we are.  Those that used to die young from (name your ailment) now live long lives to reproduce.  Those genes that would have never survived in the past, are now being passed down through the generations.

For those that can't properly comprehend this statement, I'll clarify.  No one is calling for people to be eradicated and no one is saying they shouldn't be allowed to live.  These are simply facts about where we are as humans and how we got to this point.