I do think it is very important that the religious communities do try to bring their teachings and their insights to bear on the stem cell debate and on the debate about genetic engineering.

A better way to mutual respect is to engage directly with the moral convictions citizens bring to public life, rather than to require that people leave their deepest moral convictions outside politics before they enter.

Parental love is not contingent on the talents and attributes the child happens to have. We choose our friends and spouses at least partly on the basis of qualities we find attractive. But we do not choose our children. Their qualities are unpredictable, and even the most conscientious parents cannot be held wholly responsible for the kind of child they have. That is why parenthood, more than other human relationships, teaches what the theologian William F. May calls an “openness to the unbidden.

It is true that the Jewish tradition emphasizes the moral mandate to save life. It also has a different position from the Catholic Church on the moral status of the embryo. It has a more developmental view of when human life, in the sense of personhood, begins than does the Catholic Church.

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.

In most of our lives, we are accustomed to aiming at mastery and control and dominion- - over nature, over our lives, over our jobs, over our careers, over the goods that we buy.

My argument is not that we must never intervene in nature. My argument is that there is a moral difference between intervention for the sake of health, to cure or prevent disease, and intervention for the sake of achieving a competitive edge for our kids in a consumer society.