Professor Ian Wilmut says human IVF embryos should be cloned to help couples with hereditary diseases give birth to healthy children.

After producing an identical twin of the original embryo, minus genetic defects, the original would be discarded.

Opponents say the technique would usher in a new era of genetically modified babies, with scientists playing God by deciding which imperfect embryos would not be given the opportunity to live.

Overcoming Genetic Defects

Prof. Wilmut previously said he was "implacably opposed" to using cloning on human beings.

But in his book After Dolly, the Edinburgh University expert now says using genetic modification on an embryo of 100 cells would not have the same moral implications as reproducing an adult.

Genetic modification would be more efficient than the current procedure of screening embryos for defects, and would allow more couples who fear a disabled child because of a genetic defect to have a family.

Into the Light

Prof. Wilmut said: "I want people to have new options when it comes to that most fundamental urge, to bring healthy children into this world.

"Use of genetic reproductive techniques is not a step backwards into darkness but a step forwards into the light."

In 1997, Dolly was cloned and genetically changed to produce human blood clotting protein in her milk.