I'm a relative novice to rationality studies, but have become fascinated with this site. I'd like to take a part in the discussions here to explore my own views and open my mind to what others have discovered. I have many friends who have read Harry Potter and the Methods of Rationality, but I haven't looked at it yet. Maybe I will, after seeing how many people here found this site through it. My academic background is mathematics, with a focus on logic and set theory, so rationality seems a logical next step in my personal growth. I look forward to interacting with all of you!
With the large number of genetic diseases that exist, it seems improbable that neither you nor your partner would be a carrier for something. So your statement would imply that most couples should use embryo screening, and possibly go through thousands of embryos to find one that is free of any genetic defects. This seems both unnecessarily costly and also unwise- without knowing more about the human genome, we can't be sure that eliminating a defect wouldn't cause worse problems. For example, we know that carriers of sickle-cell anemia are more resistant to malaria. What other correlations would we miss through haphazardly screening out carriers of other diseases?
Of course, in a case like cystic fibrosis, embryo selection is the clear choice.