Why There’ll Never Be Another You : Genetics: Cloning a sheep is not the same as cloning oneself or even siring the perfect child.

With the possible exception of a much-publicized but highly dubious case reported in the Middle East a couple of millennia ago, nobody had succeeded in cloning an adult mammal until recently. This week’s announcement of the possibility of producing genetic replicas of sheep in Scotland immediately inspired speculations about cloning people, and from one perspective, those speculations are perfectly justified: As far as molecular genetics is concerned, there is no significant difference between applying the relevant techniques to sheep or mice or men.

So, can we look forward to a world chock-full of human clones? A world in which the NBA features uniform teams--the Larry Birds, the Michael Jordans, the Shaquille O’Neals--season after season in recurrent competition? In which the 27th version of Kenneth Branagh delivers the definitive Henry V? In which a sequence of Stephen Hawkings (some perhaps freed from disease through a minor genetic modification) continues to push back the frontiers of cosmology?

No. Replicating genes, even the entire stock of genes, is a far cry from replicating people. However much you might want to bequeath to the world an exact copy of yourself, you are doomed to fail. Not only will your clone not be you, the clone may not even be very much like you, except in those rare respects in which the influence of the environment is tiny. Although the contemporary fascination with genes “for” all kinds of human traits, ranging from novelty-seeking through sexual orientation to dispositions to violence, ignores the important role that environment plays in the characteristics that matter most to us, we can hope that the point becomes sufficiently clear to prevent wealthy megalomaniacs from pursuing fruitless attempts to spread copies of themselves.

One of the striking facts often taken to indicate a powerful role for the genes in sexual orientation is the roughly 50% probability that if one member of a pair of male identical twins is gay, so will the other be. It would be equally pertinent to recognize that roughly 50% of such twin pairs will not both be gay, so factors other than genes must have a role in sexual orientation.

Even though cloning human beings is a hopeless method of generating exact copies, it can raise the probability of certain outcomes. If I were hellbent on having a child who would excel on the football field, the standard method of producing offspring would be ill-advised. My chances would be much better (although not very high) if I could persuade my wife to replace the genetic material in one of her fertilized eggs with that from one of today’s football stars. So one possible use of the new techniques is to allow those who want a child of a particular type to raise the likelihood that they will achieve their goal.

The desire to produce children who will satisfy society’s principal criteria of success runs very deep, inspiring new parents to enroll their young in the “right” schools, even in the “right” preschool programs. With the possibility of mammalian cloning, the pressure to have only children who can be certified as successes is extended into prenatal decisions. The new technology is particularly dangerous in combination with attitudes that are already widespread, that lead parents to force boys and girls in particular directions, to excel in sports, or the arts, or in beauty contests.

James Mill, determined that his son, John Stuart Mill, should be a brilliant intellectual, started him on Greek at 3 and Latin at 8. In early adulthood, young Mill suffered a nervous breakdown, from which he recovered and, indeed, fulfilled at least some of his father’s hopes. Will some future counterpart of his bear the additional burden of knowing that he was designed to be an eminent scientist or a great writer, that his genetic makeup was carefully chosen to that end? The elder Mill tried to fix what his son should be, and what is most repugnant about the prospect of cloning people is the possibility that the battle for control of another life can be carried on more effectively with biotechnological weapons. John Stuart Mill saw the fundamental point as clearly as anyone when he wrote, in “On Liberty”: “Mankind are greater gainers by suffering each other to live as seems good to themselves than by compelling each to live as seems good to the rest.”