That is really an interesting question and I must say, I don't have the faintest of clues. Both the answers will lead to even more intriguing questions like the ones you have raised here. I think we still don't understand a lot about our own selves and until we do that, this type of tech will be beyond our reach. That's why I think this could be possible, even if, only during the later part of this century, but who really knows, right? haha

Anyways, thanks for making me think even more about it :)