I am disappointed in many of the responses which you offered to Bryan on the cloning question. First, I think he is assuming that cloning can work, not postulating hundreds of unethical experiments to try to get there.
So many of you cited reasons why you didn't like it, but hardly anyone performed a sober assessment of the relevant trade-offs. It seems we get an extra person out of the deal, for one thing, and I am taken aback that a number of you would regard this person as a net negative. For others, "I can find some reason to object to this" seemed like a decisive argument. Bryan's joy in the arrangement seemed to bug the readers all the more; I had the feeling many of you would have found it perfectly OK if he had expressed resignation at something like this being an accidental occurrence.
I don't have the same preference as Bryan, far from it. I think most of us desire children who are "too similar to us" and there are obvious Darwinian reasons why this is the case. Nonetheless we should try to overcome this attitude and there are many successful instances of adopted children or various other "mixed" arrangements, such as foster parents. We can only hope there will be more and that means we need a greater flexibility of intuitions about parenting and inheritance.
As a proud step-parent, I find it increasingly odd how many of you insist on the "fifty percent solution." Ew! What if it — heaven forbid — looks like you? What if you're both economists named Keynes? But there's more: the rest of your daughter looks just like the woman you chose to marry? Yuck!!!!! And so on. Maybe you all think that fifty percent is great but one hundred percent is unacceptable, when it comes to the genes. Good luck arguing that one with a committed nominalist. And I bet most of you don't find it repugnant if a father wants a son rather than a daughter, but similarity of gender is pretty important too.
If I have any criticism of Bryan, it's that he's pro-natalist (fine in my book) but I've never heard him promote the idea of adopting a child or defend the idea of raising a biological child who is, for whatever reason, very different from his or her parents. (Don't overreact here and interpret his silence in a negative way, I'm simply goading him to take up these issues, which I think will force him to revise his thought.) Furthermore I think his intuitions about similarity, and child-rearing, will change once (some of) his kids start rebelling against him.
Most of all, I found this thread to be a lesson in how quickly smart people will side with their Darwinian intuitions, and attack another smart person with intolerance, just because something feels icky to them. It's not so different from how some people find gay people, and also "what they do," to be disgusting. They also don't want gay people to be adopting children because they see that as offensive too. It's not, least of all for the child.
That all said, I guess he shouldn't put the passage in his book.