You have the causality reversed. Either way: it is the idea itself that is bad. You demonstrate it kind of beautifully on this thread. Is there moral complexity to conceiving children with a significant likelihood of inheriting Huntington's? Absolutely that's a complex question. But even you, doing your best to put the idea in its best light, couldn't keep yourself from sliding into questioning whether the "sickly" and the "low IQ" should exist.

This idea chews up people's humanity. You've had an opportunity to play around with it harmlessly on this thread. Now recognize it for what it is and stomp it to death under the heel of your shoes, taking some satisfaction as you do.