The DNA of Politics

“Are Political Orientations Genetically Transmitted?” by John Alford, Carolyn Funk, and John R. Hibbing, American Political Science Association, May 2005, (from Nebraska Liberation Front).

Today I attended Dr. John Hibbing fascinating lecture on the role of genetics in politics. His powerpoint was excellent, though I do not think he wants to make it generally available. Instead, I found a link to a scholarly article Dr. Hibbing has written that discusses some of the same points.

For those interested in the scientific details, please read the original article. Alternatively, at the end of the article I am putting some footnotes to allow one to read details without having the post bogged down by “boring stuff.”

A political survey was given to many pairs of fraternal and identical twins. Fraternal twins are brothers or sisters that just happened to be born at the same time, while identical twins are genetically identical (identical twins are “clones” of each other). [1]

Using some math, the similarities and differences in answers between the sets of identical and fraternal twins were used to calculate environmental and genetic factors. [2] It did not matter is identical twins were raised as identical twins, raised as fraternal twins, or otherwise brought up. [3]

Every question was at least somewhat influenced by genetics and at least somewhat influenced by the environment. The least genetic — those were “nurture” mattered the most and “nature” mattered the least — were a person’s party affiliation and their view of “liberals.”


This makes sense. A party affiliation is basically a club, while in American politics “liberal” is used as an insult by almost everyone.

Interesting, while one’s own party was almost entirely “nurture,” “nature” was about twice as important in what one thought of the parties. That is, while it was almost genetically random what party you are, your genetic heritage — your “nature” — determines a littlw aht you think of the Democrat Party and the Republican Party


Yet, other factors are genetically more related — particularly things involve money and blood:


What political issue is most closely tied into genetics? What political move would run into the deepest, most ingrained hostility?

School prayer.


There are many reasons that Conservatives may want to be thankful to the Warren Court, but Envel v. Vitale, which banned school prayer, is one of the biggest. The unique factors of American political culture make school prayer a center of gravity — what the Germans called a “schwerpunkt” — in the defense of conservatism. A smart liberal would try to go around it, as water goes around mountains.

Earl Warren was not a smart liberal.

In one swoop the Warren Court threw the progressive movement against the genetic/conservative schwerpunkt of prayer in schools.

That “liberal” is now an empty insult is a testament to Mr. Warren’s work. So is the Bush Presidency, the Republican Congress, and the Court.

Footnote 1: On Identical and Fraternal Twins

“The process of identifying in the laboratory the precise genes responsible for given human behaviors (especially those behaviors that do not have corollaries in lab-friendly animals such as mice) is extremely challenging. Fortunately, even without identifying the genes responsible, it is possible to compile information on the matter of most concern to social scientists: the extent to which attitudes and behaviors have a genetic component. The relevant procedures center on comparisons of monozygotic (MZ; frequently but erroneously called identical) twins and dizygotic (DZ; fraternal) twins.

“MZ twins develop from a single egg, fertilized by a single sperm, and share an identical genetic inheritance. DZ twins develop from two separate eggs, fertilized by two separate sperm, and are in effect simply two siblings that happen to be born simultaneously. As such, DZ twins share the same average of 50% of genetic material as do any two biological siblings. It is this fixed ratio (two to one) of genetic similarity between MZ and DZ twins, and the contrasting average equivalence of environment influence, that provides most of the power of twin designs. It is important to appreciate that the assumption of environmental equivalence is one of equivalence across types of twins, not across pairs of twins or across twins within a given pair. For example, there is undoubtedly at least some variability in parental socialization across siblings, even those of identical age, but acrossmultiple twin pairs the assumption is that this variability is essentially equal for the MZ and the DZ pairs.”

Footnote 2: Mathematically Seperating Environmental and Genetic Factors

“Heritability is typically estimated by subtracting the correlation for DZ pairs from the correlation for MZ pairs and then doubling the resulting difference.At one extreme, if the correlations are the same for MZ and DZ pairs, suggesting that genetic similarity plays no role in similarity for that particular trait, then the result will be an estimate of heritability of zero. At the other extreme, a purely genetic additive trait should produce a correlation of .5 for DZ pairs and 1.0 for MZ pairs, resulting in an estimate of heritability of 1.0 (1.0−.5=.5, and 2 x .5=1.0). In a similar way, we can estimate the influence of shared environment, as opposed to shared genetic material, by doubling the correlation for DZ pairs and then subtracting the correlation forMZ pairs. Again, a purely genetic additive trait should produce a correlation of .5 for DZ pairs and 1.0 for MZ pairs, resulting in an estimate of the impact of shared environment of zero (2 x .5=1.0, and 1.0−1.0=0). At the other extreme, if the correlations are the same for MZ and DZ pairs, suggesting that genetic similarity plays no role in similarity for that particular trait, then the result will be an estimate of the impact of shared environment that is equal to the MZ or DZ correlation (e.g., if MZ=DZ=.4, then 2 ∗ .4=.8, and .8−.4=.4). Whatever is left over is taken to the unshared environment.”

Foonote 3: It Does Not Matter How the Identical Twins were Raised

“Both caveats have been subject to sustained and varied investigation and neither has been found to hold up under empirical scrutiny. The argument of more similar treatment fails on several fronts. Parents frequently miscategorize their twins (DZ twins are often believed by their parents to be MZ twins) and the differential correlation persists in these instances of miscategorization. In other words, the degree of correspondence betweenMZtwins surpasses that of DZ twins even in the large subpopulation of twins thought by their parents to beMZtwins (Bouchard and McGue 2003; Bouchard et al. 1990; Plomin 1990). The contention that MZ twins have closer or more frequent contact than DZ twins turns out to be at best irrelevant. The correlation between the frequency of contact between twins and the similarity between twins on all attitudinal andbehavioral variables tested, including conservatism, is slight and actually negative (Martin et al. 1986). In other words, twins in greater contact with their cotwins are not more likely to share the same attitudes and behaviors, so even if MZ twins have more contact than DZ twins, this contact is not the cause of any elevated correlations. But the most powerful refutation of both of these criticisms comes in recent studies utilizingMZ and DZ twins raised apart. These studies uniformly validate MZ and DZ differences found in earlier studies of twins raised together. Arguments about the relative degree of shared environmental effects between MZ and DZ twins simply offer no credible explanation if the twins in question have been raised apart (Bouchard 1998; Bouchard et al. 1990). In effect, this naturally occurring, if uncommon, condition provides precisely the sort of laboratory control that we would want in an experimental setting.