Like all really scary stories, this one started with a purely innocent being: a little lamb whose fleece was white as snow.
But when Dolly the sheep was born in 1996 -- making her the first mammal to be cloned from the cell of another animal -- it raised the very real specter that humans, too, might be duplicated in the foreseeable future. While there are no documented cases of human cloning so far, some experts think it's just a matter of time.
