Your criticism is difficult to follow. There's a big difference between refusing an intervention and making use of one. I can licitly refuse treatment for a dis

Your criticism is difficult to follow. There's a big difference between refusing an intervention and making use of one. I can licitly refuse treatment for a disease (the distinction between ordinary and extraordinary care), but I cannot licitly make use of immoral means to treat a disease. > If we allow parents to destroy embryos, why is it so controversial to allow them to modify them? Genetic modification as such, in the abstract, when therapeutic (fixing some genetic defect that causes a disease) may be licit in principle, but in practice, 1. our ignorance of genetics and non-trivial hereditary effects suggests we should be cautious, not only for the sake of the person whose genes are being edited, but because the change is not localized; that modification may not be transmitted to descendants 2. that embryos are subjects of modification introduces the standard moral problems of IVF (such as the objectification of human beings). If modification is not therapeutic, then the usual moral problems surrounding designer babies apply in addition to those that apply to IVF. Killing embryonic human beings is intrinsically worse, though the secondary genetic risks are obviously absent.