Dismay at Dolly's cloning brought a flurry of legislative proposals to protect humans from suffering a similar fate. This knee-jerk reaction stemmed less from any perception of immediate danger than from general angst that the power of molecular biology is turning rapidly toward our own reproduction and targeting the very heart of human identity. Manipulation of even our germline can no longer be dismissed as a matter for future generations.

There is little doubt that the possibilities to come will tax our wisdom, but this is no reason for bans and fearful denunciations. UNESCO's draft declaration that human cloning and germline engineering are "contrary to human dignity" is sheer ignorance. What real-world dangers do we face that might warrant so premature a repudiation of the therapeutic possibilities inherent in these scientific breakthroughs?

The potential medical benefits of genetic engineering are too great for us to let...