Human Stem Cell Cloning: 'Holy Grail' or Techno-Fantasy?

(CNN) -- Today was a strange day. I'm used to handling the brief but overwhelming burst of media attention that comes with new stories about medical breakthroughs and ethical issues. But I don't often get an accompanying deluge of passionate e-mails and phone calls from people who had read my comments, denouncing me for criticizing science, especially medical research that "can save millions of lives."

There is definitely something special about this idea of "therapeutic cloning," something that has a religious feel to it. Most of those messages come from people who have family members suffering from some of the diseases that we are told will be cured, and it's hard to have to pour cold water on people's hopes.

I feel really angry at the scientists and PR people who have sold the idea of cloned human stem cells to so many patient support groups, when there is so little scientific substance to their promises. We are told that there will be great medical benefits and that the risks that there will be cloned babies are small, but in...