embryos

Researchers disabled a gene that they think helps determine which human embryos will develop normally. The technique they used is controversial because it could be used to change babies' DNA.

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.