AFAIK, there are two main issues. The first is ethics which is pretty much obvious. Experiments on human are not easy to get approved and near impossible for th

AFAIK, there are two main issues. The first is ethics which is pretty much obvious. Experiments on human are not easy to get approved and near impossible for things like permanent changes to babies and fetuses. There are ethics boards on every company and university that regulate these stuff and they would almost immediately deny all request or proposal that approach this kind of work. You may get something going in less regulated countries like China but even then the international research community would not be kind to you and your career. The second is theoretically, it still is not possible to "design" a baby. In biology, things are very different from pure engineering. The ways stuff gets discovered is like this: if you have a big clockwork machine, you increase signal to a gear, you notice the machine do X, you say that gear is associated with X function. Then you go to another gear, do it again, and try to map out everything in the machine and their function. Cool. Now the problem is you don't know interactions between gears. So you try to change 2 gears that both associated with X. Turn out when you do that, the result is not just X but XYD get changed. Then when you try 3 gears at the same time, turns out it changes XMA function. Worse, in another supposedly identical machine, changing gear X actually causes Y change because of a previously unknown gear that is a switch for gear X to affect either X or Y and that switch depends on some obscure environment parameters... In short, biology is too complex and the way we are probing it is still too primitive and it takes a long time to even figure out what go where. We can try poking around to optimize one thing but it always causes unintended effects, mostly lethal. So the ethics boards are even less likely to approve a project like this. Just as an example: CRISPR system. We know about nucleases and these enzymes and stuff for decades. But to make it something reliable enough to be used took so long this thing only became big recently. Biology is very slow and very tedious. It won't be like writing a software and wait 10min for it to compile. Experiments can take years to run and come out with nothing because a stupid mistake was made somewhere along the way.