Because we've already done it with plenty of other animals, even cloned them and let them grow to maturity. Never heard of Dolly? We've been at a point, where

Because we've already done it with plenty of other animals, even cloned them and let them grow to maturity. Never heard of Dolly? We've been at a point, where it's viable for human application, for quite a while. But the ethical and religious stigma is preventing us from going the full distance. As of right now, it is very likely that the first genetically engineered/enhanced human will be a Chinese person because they are way more pragmatic about those issues.