If anyone here wants to see the most shocking, sad, frightening pictures ever, look at a harlequin baby. This is the kind of stuff that could startle even the most hardened doctors. It's also a congenital genetic disorder.
WARNING: Don't look at this stuff if you're not close to being borderline psychopathic and emotionless. Even I was taken back for a few seconds.
Here are some other nasty genetic problems: Tay-Sachs disease, cystic fibrosis, Huntington's disease, sickle cell anemia, and countless more. There are polygenic factors that contribute to cancer, diabetes, heart disease, Alzheimers, autism, and depression.
We could eliminate these horrifying diseases (not the polygenic ones, of course) if carriers (people with 1 copy of a gene, but are not affected) would abstain from breeding. Selecting for intelligence and other things is more controversial, but I can't see how anyone would want to spread diseases. We could improve the biological quality of the human race and stop a lot of suffering for generations on end.
I think people should get tested for these terrible diseases. At the very least, they could breed with a non-carrier. Their children won't be affected by a diease, but there's a 50% chance for them to be carriers as well. If 2 carriers breed, 25% of their children will be affected, even though 25% will be noncarriers. The last 50% would be carriers.
At a point, we should stop blaiming environmental toxins, and take personal responsibility for our defects. It doesn't involve forced sterilization or genocide. It just requires personal responsibility, a true conservative value.
EDIT: Forgot to post the big list of diseases.
http://en.wikipedia.org/wiki/List_of_genetic_disorders