If we go too far down the road of choosing the genetic traits of children, my worry is that parenting will be less a kind of school for humility than it should be, and we will become too accustomed to regarding children as instruments of our ambition and of our desires.

If you go back to Adam Smith, you find the idea that markets and market forces operate as an invisible hand. This is the traditional laissez-faire market idea. But today, when economics is increasingly defined as the science of incentive, it becomes clear that the use of incentives involves quite active intervention, either by an economist or a policy maker, in using financial inducements to motivate behavior. In fact, so much though that we now almost take for granted that incentives are central to the subject of economics.

The way things are does not determine the way they ought to be

It's true that to speak of an ethic of giftedness, which is very much the ethic that I deploy in raising questions about designer children and genetic engineering - an appreciation of the giftedness of the child or the giftedness of life does have religious resonance, because a great many religious traditions emphasize the sense in which the good things in life are not all our own doing; they are gifts from God.

I think people who want to use genetic technologies to gain a competitive edge for their children are engaging in a kind of overreaching that could really undermine our appreciation of children as gifts for which we should be grateful and, instead, to view them as products or instruments that are there to be molded and directed.

Whether you're a libertarian liberal or a more egalitarian liberal, the idea is that justice means being non-judgmental with respect to the preferences people bring to public life.

One can imagine a kind of hormonal arms race or genetic arms race, whether it's to do with height or IQ, conceivably, in the future. So it's limitless, and that's another of the features that sets it apart from medical intervention.