I see nothing wrong ethically with the idea of correcting single gene defects [through genetic engineering]. But I am concerned about any other kind of intervention, for anything else would be an experiment, [which would] impose our will on future generations [and take unreasonable chances] with their welfare ... [Thus] such intervention is beyond the scope of consideration.

It is difficult to imagine a greater imposition [than adding] genes to future generations that changes the nature of future people.

The pressures for human cloning are powerful; but, although it seems likely that somebody, at some time, will attempt it, we need not assume that it will ever become a common or significant feature of human life.

What politicians do not understand is that [Ian] Wilmut discovered not so much a technical trick as a new law of nature. We now know that an adult mammalian cell can fire up all the dormant genetic instructions that shut down as it divides and specializes and ages, and thus can become a source of new life. You can outlaw technique; you cannot repeal biology.
Writing after Wilmut's successful cloning of the sheep, Dolly, that research on the cloning of human beings cannot be suppressed.