Always of course the concern is applying genetic technology to humans, and that's where the real ethical problems arise. There's an excellent book on this subject called Remaking Eden, which came out last year by my friend Lee Silver, who is a biologist here in Princeton. And he's looking mostly at fertility clinics and I think he's absolutely right, that's where the action is. That it's not... it's not the scientists who are really responsible in this area, it's the medical people, and the fertility clinics are an enormously profitable industry driven by the passion of parents who have to have babies. Parents who go to the fertility clinics are willing to stop at nothing to get babies, and also when they get babies to get good babies free of genetic defects. So that's the driving force. The parents will always take advantage of any technology that comes up to make sure that they can have babies they can call their own, and this is somehow a very, very basic human need, and it's not just in the rich countries but in the poor countries too that this is now a very profitable and... and growing industry. And it's... it's not going to be easy to stop if you wanted to stop it. I think that's the problem, and I think we have to face it, that people are going to use these technologies as soon as they become available. There have to be some legal limits, and the obvious legal limit is to say that you should never apply any technology to produce babies that you don't have reason to believe is going to work. I mean that... you should not take undue risks to produce defective babies. What is an undue risk? Roughly, the risk of producing a defective baby should not be greater than it is naturally, which is already quite high. The risk of genetic defects in a natural birth is about 4%, so that you can allow yourself risks below that level and it still improves on what nature can do. But further than that, I don't know. It's very hard to know where to draw the line. I think Lee Silver has looked at it rather carefully and his conclusion is basically laissez-faire, that it's very hard to intervene in some human... where we are dealing with, sort of, basic human desires and needs, which... which are so passionately felt and so widely felt.