If you mean genetic illnesses that will be life threatening or severely affect the child's quality of life, then I agree with you. That risk just isn't worth taking. However, I still think that if the risk isn't that big or that the illness in question isn't particularly severe, then maybe it's worth taking the risk. Besides, the final say on this issue should be with the people who are actually having the child. There's plenty of other options too if the couple still want to have a child as well, adoption being the first one that comes to mind. I'm also intrigued to see all this talk about autism, ADHD and other 'disabilities' in this thread as well. I'll comment on those a bit later, but I think I need to refine my argument a little bit.