On Facebook, I opined that boosting libertarians’ Total Fertility Rate to 3 is the most realistic long-run path to liberty.  The underlying assumption is that political philosophy, libertarianism included, is fairly heritable.  Will Wilkinson then presented an interesting objection:

if personality is passed along genetically, and personality has a lot
to do with our political sympathies, the way those sympathies are
expressed at any time is a cultural matter. The difference in the
content of American conservatism
now and thirty years ago is large. Likewise, in a generation, the
ideology most attractive to those with a psychology that inclines them
toward libertarianism will undergo cultural evolution and may not be
recognizably libertarian in two or three generations. I think there’s a
good chance that had Bryan and I been born in 1910s, instead of in the
early 1970s, we would have been communists.

Will’s basic point is sound: People alive in 1910 adopted different political philosophies than they would have adopted in 2010.*  But his appeal to “cultural evolution” is needlessly vague.  The key difference between 1910 and 2010 is that people in 1910 were exposed to a narrower range of political philosophies during their formative years (roughly ages 15-25).  Libertarianism was outside that range.  As a result, even people genetically predisposed to libertarianism failed to adopt it before their minds closed.

In the modern world, however, political genotypes are much more likely to translate into matching phenotypes.  During the 20th century, political philosophers
covered most of logical space.  And thanks to the Internet, almost
everyone hears about views likely to appeal to them before their formative
years end.  The upshot: If you’re genetically predisposed to
be a libertarian, Leninist, social democrat, conservative, liberal,
green, or liberaltarian, you now discover that position during your
formative years and adopt it.

Application: During the 60s and 70s, few libertarians had libertarian relatives.  Many tried to convert their parents, but few succeeded.  When I talked to the Students for Liberty, however, about half had at least one libertarian parent.  These patterns are just what my story predicts.  The parents of the older generation of libertarians didn’t hear about libertarianism during their formative years, so the trait never expressed itself.  The parents of today’s college students, in contrast, usually experienced the key environmental catalyst in time.

If novel political philosophies emerge in the 21st century, a new political generation gap could easily emerge.  Otherwise, I expect the match between political genotype and political phenotype to get pretty tight – and the political generation gap to shrink back to its pre-modern levels.

* Personally, I doubt either Will or I would
have been communists for long; the groupthink would have been too
much to endure.

Update: Will fleshes out his argument.