A kind email:

You’re too hard on yourself. You did fine. One thing you could have done differently though is to start out the discussion of euthanasia by setting forth definitions. You say that you disagree with the other guy [Robert Wright] about what the typical case of euthanasia is, but that may be because you would consider cutting off food and water to someone in a vegetative state as euthanasia while he is thinking more of an assisted-suicide case–and you are quite right, of course, that the former happens a lot more often than the latter.
I’ve been reading the comments on the bloggingheads site. I don’t know if you do. [Sometimes. It’s a vice.–RP.] The folks who want to argue with you, as opposed to complaining about your religion, are noting that the reprogramming of a cell to produce embryonic stem cells is “no more natural” than IVF, and so you have no grounds for opposing one and not the other. Wow.
Anyway, loved the book, keep up the great work.

Thanks; you might be right about the euthanasia point. Unless there’s something more to it than this reader is explaining, that would be a weird argument–nothing in my position on embryo-destructive research turns on what’s “natural” or “unnatural.” The point would be that stem-cell research on embryos taken from fertility clinics involves destroying those embryos, whereas the reprogramming does not involve the destruction of any embryos. I don’t think that’s so hard to grasp.