The rest will have unpredictable but potentially devastating health problems. Those problems are not detectable before birth, because they do not come from genetic defects as such they arise from the disorganized expression of genes, because cloning plays havoc with the usual process of genetic reorganization in the embryo. Cloning is, in fact, the perfect reproductive technology for dead people. All one may need is a nail clipping or the hair left behind in a comb. But perhaps a deeper problem with human cloning is what it would do to our attitude toward the child.
Cloning is the ultimate depersonalizing of human reproduction.
That openness, and the unpredictability of how the traits of husband and wife will combine in a new individual, expresses the fact that this child is our equal in human dignity, a new person with his or her own open future. Even if identical twins occur, each of them has this unpredictable combination and this newness. Cloning is just the opposite. Children are manufactured in the lab to preset specifications. They do not arise, but are constructed.