> That should be entirely down to the parents.

When making decisions that will affect (in planned and unpredictable ways) the phenotype of a person over their entire life course - society / medical experts and researchers etc necessarily need to have a say.

We can't beat or euthanise our children, neither should we have carte blanche over their genetic makeup.

Note - I'm not suggesting that we shouldn't employ gene modification to ameliorate health issues or even to improve other metrics. However this is absolutely not just 'down to the parents'.