This all sounds great but you're somehow forgetting that there are somewhere around 100.000.000 million humans alive today with genes defective to the point tha

This all sounds great but you're somehow forgetting that there are somewhere around 100.000.000 million humans alive today with genes defective to the point that they will kill their owners/hosts/whatever you want to call them. Just in kids, there's going to be something like 1 million kids currently alive that don't have a beating heart. Babies don't actually need their heart to be beating, diffusion will provide plenty of oxygen to their organs and brains. They may not have a heart at all (that's rare though, more likely it has a hole big enough to disrupt things enough that it won't keep beating, although even a needle sized hole will kill them if it doesn't close). These kids will, inevitably, grow. And their growth will kill them. The strongest among them will live something like 2 years. 50 times as many kids will have a degenerative disease. This may go from Leukemia to other blood issues right to ALS or MSC or CF. They will generally start dieing off at 6-8 years and some will grow to 25 or so. But they will die. And just in case you think 25 is nice, MSC/CF kids will feel like they're drowning constantly, 24/7, starting at ages 5-8. ALS is even worse. And yes, I get it, stephen hawking grew to 76. But he is an incredible exception and that was only possible with constant, 24/7/365 nurse attention. It is not generally possible. Even for people who get that 24/7/365 attention he grew to literally double the age of the next patient. And let's just not talk about people with brain misgrowths or epilepsy. Let's just not talk about how horrible that is. Half of them will never have the intelligence of a 3 year old, but they're still mostly in constant pain. Another roughly-same-size batch will have a serious defect in their bodies that isn't readily apparent. They will suddenly fall ill, and go from happily going to school to dead in 2 months following at essentially a random time. Not because of a disease or condition, but because their bodies really, really can't deal with things that are overwhelmingly part of our environment, going from UV light to pressure differences, to water, some insects, ... That's the damage our own genes put humanity through. In total somewhere between 2% and 5% (depends on your ethnicity) of people have a serious genetic defect (something that will strongly affect them until the day they die). About 1% will die from it, mostly while very young. Clearly, despite the potential for abuse (although some of your examples ... are they even abuse ? Mostly not from the only perspective that matters, that of the kids), there is a massive potential for improvement of the human condition as well.