Yes, gene therapies are a potential game-changer….
And yes, at one time diseases wiped out so many children (whooping cough for example) that parents had five kids to ensure one or two heirs.
As for children being a private matter, it seems like a pretty personal space in which to allow government to decide. End of life, too. Should government decide how long people live? That’s going to be expensive, too, when the science enables people to live longer and longer. If it costs big bucks, the rich will pay for this (who want it) but then our egalitarian beliefs will say it is unfair for rich to have something the poor can’t have, so then the State (our taxes) will pay for it for everyone.
Once the State is footing the bill, there is going to be a decision made at some point that at age “X” no more funding. Brave New World might be closer than we think.