cloning

Researchers are inching closer to creating human eggs and sperm in the lab that carry a full complement of anyone's DNA. It could revolutionize fertility treatment and raises huge ethical questions.

The news that scientists have successfully cloned a human embryo seems almost certain to rekindle a political fight that has raged, on and off, since the creation of Dolly the sheep. It's a fight that has, over the past decade and a half, produced a lot of heat and light and not a lot of policy.