[GoldenRacer]

What genes do you think we should be testing for and which ones do you think are severe enough that you parents with those genes shouldn't have children?

Almost everyone has some sort of gene that isn't great. They might have a family history of Alzheimer's, maybe a family history or some sort of cancer, or bipolar disorder, or any other of 100 different serious illnesses. Humans would go extinct if we only allowed those with perfect genes to reproduce.

Oh, and with sickle cell, you're going to be in particularly hot water with suggestions like that given the fact it's mostly African Americans who have the gene.

[codedokode]

I doubt this. If majority of population had severe incurable diseases then humanity wouldn't survive, and healthcare would collapse. I think (sorry, no statistics) that majority of population are healthy enough to do hard physical work.

[itishappy]

Consider that traits can be recessive (like sickle cell anemia) so a healthy population can still produce children with severe incurable diseases.

[GoldenRacer]

I never said the majority of the population has severe incurable diseases. I said that have genes that aren't great (maybe they have a predisposition for certain diseases or they're a carrier but are healthy themselves).

Also, many diseases don't effect you until after you're past reproductive age. Evolution doesn't care if you get Alzheimer's at 70 but it still has a fairly large burden on our modern day society.

Sickle cell is particularly interesting because the gene that causes it makes the carriers less susceptible to malaria. So there actually was an evolutionary pressure for people in areas with high levels of malaria to have it (which is why it's so common among African Americans). Apparently it's better to die of sickle cell at 40 after you've had kids then die of malaria when your 10.