The issue here is that with this approach we have to ask who has to be limited next. Especially if you get older...

>>>You can‘t seriously tell me it‘s not extremely unethical for people with huntington‘s disease or cystic fibrosis to have children. Don't flatter yourself - your genes are basic and ridddled with bad genes. You do not know what time bomb you are carying in your DNA.

The solution that you are offering is quite simple - procreate early as possible and die not in old age and voila - there are no issues in more than 99.99% cases. But something tells me that you are already older than healthy monkey and do not plan to live in a tree - your bones are too old for that and thanks to evolution are not meant for that.

Evolution of humans in future includes even longer lifespan which naturally comes with children produced at much later age than we do now and that comes with diseases to be dealt with, as that is part of evolution. We do not know much about mutations in DNA - they are never good or bad - they are combinations of something. For example - diabetes type 2 seems to be from genes, that allowed humans to survive hunger for long period of time - are those genes bad, because people are obese nowadays? As for mentioned diseases - we value other humans not by DNA, but what they are to us. You would sing a different song, when their offspring would have any of such disease and you are in luck and not planning to have any.

Most genetic diseases only occur when two parents happen to have it, but they won't necessarily be aware of it; would it be unethical for people who are unaware of their genetic defects to have children?

Second, according to a quick search, 10% of cases of Huntington's Disease are due to new mutations; I suspect (but I'm a HN commenter, no geneticist) this is the case for many other genetic conditions.

So the other ethics question to ask: should people be able to get DNA tests for genetic conditions (voluntary)? I'd say yes. Should people be mandated to get DNA tests and be forbidden to procreate if there's something in there? No, that's eugenics. Should people who know they have a genetic condition and there's a chance their child has it too have children? That'd be their choice. I don't think it's fair for people to intentionally place a burden on health care systems like that, but thing is, there's very, very few people that have children with that as the intent.