I have friends with inherited genetic conditions and with genes that increase their risks of cancer. I wouldn’t want to decide for them, but I wouldn’t have any moral objection to them wanting to alter the genes in question to avoid their children having the same medical challenges.
Good question! For me, personally, I think if we could alter genes to avoid passing on medical problems that would be morally OK. But obviously, people may then want to take this further and change genes for eye colour, pick their babies gender, make them more sporty etc etc. This is when I think we start facing ethical problems.