An Indiana official publicly apologized for the state's role 100 years ago in pioneering state-authorized sterilization of "imbeciles," paupers and others it deemed undesirable. (click paragraph for original article)
Eugenics and therapeutic abortion for birth defects are essentially the same moral issue:
Are humans expert enough at social genetic engineering to replace whatever nature is doing now (which, apparently, no one knows) with their own version of breeding: smaller, smarter, less violent, less prone to cancer, bleeding, heart attacks, obesity.
Abortion is, sometimes, a crude and sloppy way to deal with a problem that could have been prevented.
As genetic engineering improves, the ambit of cures is going to expand. In countries with strong cultural reasons, boys are born, by ultrasound and abortion, more often than girls.
Tay-Sachs is screened for, as are many other diseases and infirmities.
Then you have the Steven Hawking argument, "You can't predict 100%" which is essentially an abdication of responsibility, an expression of "Let the perfect be the enemy of the good."
Where do you stand? Have you thought out the ramifications of your position? Do we want 10,000 ALS patients on the off chance we'll get a Hawking?
Do we want to load down our medical and social facilities with thousands of people with predictable severe handicaps because "retarded people are happy people"?
I speak to this from fifteen years of taking care of fifty-plus ARC members at one of the best facilities in the United States.
My fellow attendants were all over the spectrum, sometimes, especially after one of the patients died or suffered badly from their condition. It's hard to be "happy" when your spine aches like knives in your back.
It's easy to advocate against genetic screening, the technical name for eugenics, leaving the care of the poorly made to others, and as is so often the case, dumping them into snakepits on the (unexpressed) excuse that they don't understand their own sorry plight.
A deep existential question, not one to be countered with a kneejerk discomfort reaction.