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.

The majority of American states had laws by the 1930s that allowed for forced sterilization of socially undesirable categories of people, so-called feeble-minded, for example, and with Hitler culminating in genocide.

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

I would include non-medical sex selection as one of those practices that I think is morally questionable and that can carry adverse social consequences.

Today if you look at most economic textbooks, economics is not defined by subject matter. It's presented as a science of social choice that applies not only to material goods - not only to flat-screen televisions - but to every decision we make, whether it's to get married, or to stay married, whether to have children and how to educate those children, or how to look after our health.

What I really want for my children is that they be loved and that they be happy and that they lead a good life.

I am trying to get at the moral arguments and the ethical status of various attempts at enhancement, or genetic engineering, or the bid for designer children. But there are implications for society at large.