We — at least, Jonah and I — have sometimes kicked around the ideas of Judith Rich Harris here on the Corner. This is the writer whose book The Nurture Assumption tried to explode a lot of the conventional wisdom about child-raising. Sample:

Group socialization theory makes the following prediction: that two biologically unrelated children of about the same age who are reared in the same home will be no more alike in personality and behavior (measured outside the home) than two biologically unrelated children of about the same age who are reared in different homes but who live in the same neighborhood and go to the same school.

In a nutshell: parenting style, away from dire extremes, doesn’t matter.

Well, this year is the tenth anniversary of The Nurture Assumption and we are getting some good follow-up comment. Here’s one from child-development specialist Helene Guldberg, taking mild issue with Harris from an existentialist point of view.

And human beings are determined neither by nature nor nurture … We are active agents who engage with, and have the capacity to shape, the collective culture of our time.

That’s incoherent. You can argue about the relative influences of nature-nurture (Ms. Harris thinks about 50-50, which agrees with my own child-raising experiences), but to say that neither thing determines us — that our own “active agency” does the trick — is absurd. My own active agency might lead me to prefer Coke to Pepsi (though even that is debatable). That my own active agency might cause me to be gregarious rather that solitary, energetic rather than lazy, considerate rather than selfish, or athletic rather than bookish, seems to me exceedingly improbable. Who believes it?

It’s a bit odd that Helene Guldberg doesn’t mention Judith Rich Harris’s second book, No Two Alike, which I thought even more thought-provoking than the first one — a better and more interesting book, in fact.