If parents are aiming at choosing children who will be good athletes, or great musicians, or who will get into Ivy League schools, or who will be tall enough to make the basketball team, then there is a danger that the life of the child will bear the burden of that expectation; and the risk of disappointment and the cost of disappointment will be even higher than they are now, and even now they can be considerable.

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.

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.

In natural pregnancy, more than half of fertilized eggs fail to implant or are otherwise lost. Should we regard that as an instance of infant mortality? And if so, why are we not mounting ambitious public health campaigns to try to save and rescue all of the fertilized eggs that are lost in natural pregnancy? We would need a public health campaign of massive proportions if there really were over a fifty percent rate of infant mortality.

Human beings are empowered to exercise dominion over nature and even to be participants in creation; and yet, at the same time, there are strictures against idolatry, which is a kind of overreaching and confusing human beings' role with God's.

One of the ways in which parenting is a learning experience and an opportunity for moral growth is that we learn as parents that we don't choose the kind of child that we have.