Thanks to everyone who responded to my Zac Gochenour-inspired poll on parents, children, and libertarianism.  Most of the responses seem consistent with Zac’s initial doubts:

I’m trying to determine if “strategic
fertility” is nonsense or not. I find it one of Bryan’s stranger claims.
None of the libertarians I know personally have libertarian parents, but I
don’t know too many people well enough to know much about their parents’
political views. Bryan bases his claim on behavioral genetics research, but I
can’t take that research seriously if it flies in the face of everything I’ve
experienced and my intuition.‘t take that research
seriously if it flies in the face of everything I’ve experienced and my
intuition.’t take that research seriously if it flies in the face of everything
I’ve experienced and my intuition.’t take that research seriously if it flies
in the face of everything I’ve experienced and my intuition.

Or to be more precise, most of the responses on parents seem consistent with Zac’s initial doubts; for kids, there just wasn’t much data in the comments.  This is pretty much what I expected from my first-hand experience.  Still, I don’t think strategic fertility is even close to “nonsense,” and now’s a good time to explain why.  But first, three caveats:

Caveat #1: Zac seems to be questioning the largely uncontroversial view that politics runs in families.  I was making the more controversial claim that politics is hereditary.  Of course, if politics doesn’t run in families, then it’s not hereditary either, so Zac’s challenge is still on point.

Caveat #2: As far as I know, no one has ever specifically studied the hereditability of libertarianism.  I was building on the literature on the hereditability of politics within the normal range.   Note, however, that twin studies do confirm the heritability of political positions relevant to libertarianism – including “socialism,” “censorship,” “open-door immigration,” “voluntary euthanasia,” “making racial discrimination illegal,” and “capitalism.” (See here and here).  So I’m not generalizing that far outside the normal range.

Caveat #3: For a trait like self-identified libertarianism held by maybe 1-2% of the population, even a 20% concordance rate between parent and child would indicate strong familiy resemblance.  After all, it’s 900-1900% above the base rate.

Caveats aside, though, I have noticed a puzzling pattern: Older libertarians rarely have libertarian parents, but often have libertarian children.  Younger libertarians, in contrast, don’t yet have children, but often have libertarian parents.  Here’s my explanation:

As the great Mosca observed in chapter 7 of The Ruling Class, people usually acquire their political convictions in early adulthood, then ossify.  This certainly doesn’t rule out genetic influences on politics.  But it does strongly suggest that early exposure to a viewpoint is an important catalyst to its acceptance. 

Now note: If you’re genetically predisposed to a conventional political outlook, it probably doesn’t matter what your parents think.  If they don’t teach you about liberalism or conservatism, you’ll pick it up on the street.  In contrast, if you’re genetically predisposed to an obscure political outlook like libertarianism, parents could easily matter.  If you don’t hear about libertarianism from your folks, you might never hear about it.  Or you might not hear about it until you’re 30 – when you’re no longer willing to rethink your views. 

Why then would libertarians be so much more likely to have libertarian kids than libertarian parents?  Simple: By the time you’re able to talk politics with your parents, they’re already ossified.  If only you’d talked to them when they were 17, you might have changed their minds.  In contrast, if your kids are genetically predisposed to libertarianism, simple exposure to you is probably all the catalyst they need.

Two predictions that come out of this analysis:

1. Now that the internet is ubiquitous, libertarianism is no longer obscure.  Almost everyone genetically predisposed to libertarianism probably hears about it before their political outlook ossifies.  So I predict that the next generation of libertarians will have much more libertarian parents than mine did.

2. The internet and thriving libertarian sub-culture have also probably increased libertarians’ assortative mating.  (Come to think of it, that suggests another fun survey to run).  As a result, libertarians will be increasingly likely to have libertarian kids.

Bottom line: The assumptions underlying my strategic fertility argument are messier than I’d like.  Maybe I’m just going too far beyond the data.  But I don’t think so.  As long as you read twin studies of politics with Mosca’s insights in mind, you should expect obscure political views like libertarianism to mask family resemblance for one generation.  Then family resemblance re-emerges.