There are several different questions to be asked on this subject.
One: Should people with serious disabilities or diseases (that may be hereditary) be allowed to reproduce?
Two: How do you feel about people choosing their mate based on bloodline, in an attempt to create superior children, instead of choosing someone because you love them? And would you do/have you done this?
Three: The reverse of the last question, and silly, but if someone with a hereditary disability intentionally attempted to create a baby with those flaws by finding a partner with the same problem, what do you think their intent would be by doing that, aside from stupidity? Just something goofy I found from a crazy guy on the internet, and figured it would be something to ponder.
Please answer all of the questions and try not to deviate from the original topic too much.