I think about this alot. I dont see the human population going through more evolution but mixing up different traits from all over the place no matter what they're for. It does'nt seem like much of a problem untill you think about the impact on a familys resource$ when a loved one needs some kind of major medical work done such as surgery to remove a brain tumor or the resources put forth by an entire community to help find better treatments for brain tumors. I'm not saying we should throw the genetically inferior off a cliff but being in that kind of delima will deffinately alter a family's future.
This philosophy probably does'nt cover most scenarios but it's true to some extent. Im pretty confident in my genetic makeup so far seeing as how im only 17. My dream is to live in a geographically stable area where the effects of the inevitable global issues arising wont kill my offspring.