Partisan heritability

I spend a week toward in my grad public choice class on correlates of political preferences.

Suppose Don Wittman is right that politics basically gives the median voter what she wants. And suppose further that Bryan Caplan is right that the best way of modeling voters is to model a normal person, and then to take away reason and responsibility. Where crazy political preferences come from then starts mattering - there's no necessary link between "what the median voter says she wants at the ballot box" and what the median voter would actually prefer if given a decisive choice.

We then hit onto some of the evidence on the heritability and policy and party preferences. Settle, Dawes and Fowler showed that identical twins are much closer in political ideology than are fraternal twins and suggested then that half the variance in strength of partisan attachment comes down to genes. Alford, Funk and Hibbing showed reasonable evidence of political orientation heritability, also using twins. Attitudes towards school prayer, property taxes, the "moral majority"*, capitalism, astrology, the draft, pacifism, unions, Republicans, socialism, foreign aid, X-rated movies, immigration and more were pretty strongly heritable. See Table 1 of their linked APSR paper. Jason Collins also maintains a great reading list on economics and evolutionary biology.

Hatemi, Dawes et al have a rather nice new paper forthcoming showing that these findings haven't been artefacts of particular datasets. But while they've found very strong evidence of heritability, they've also shown that links to particular genetic markers are fragile. Markers associated with ideology in one dataset don't show up in another - which is about what I'd expected. If you've thousands of genetic markers to choose from and you're searching in one dataset for ones that will correlate with preferences, you're bound to get some spurious correlations that will then fail to replicate in other datasets.

The ScienceNordic summary probably overstates things a bit - there's a pretty extensive prior literature on heritability of ideology, including many pieces by some of the authors of this one. But I will be adding the new piece to my graduate public choice reading list.

As I ask my grad students: now that you know that a reasonable part of your political views are basically set by your genes, how should you update the weight you attach to your own political views' correctness?

A few other obvious implications:

• Assortative mating has gotten a lot easier with online dating websites allowing people to screen out bad ideological matches. This will lead to stronger partisan attachment, higher variance in political ideology, and greater bifurcation over time.
• Where migration also pushes towards ideological assortment (liberals move to Boston, conservatives move to Texas), we get stronger regional heterogeneity over time. This suggests to me that more redistribution should be handled at the state rather than the federal level. 
• Bryan Caplan's right: don't bother trying to push your kids towards your ideology. Instead, if it matters to you, choose your spouse carefully and the rest will take care of itself. 

* A right wing Christian American lobby group.

Policy implications of happiness

If you spend time in the dodgier parts of the interwebs, you'll see arguments that we should replace GDP statistics with gross national happiness statistics and that government should be targeting happiness rather than GDP growth.

We economists are utilitarians; we tend to like GDP growth because it correlates with increased happiness. Sure, you'll see odd things like results showing low incremental happiness gains with increased income beyond a certain threshold, but think about how the happiness numbers are collected: by self-reported happiness on a scale from zero to ten. You start running into right truncation issues pretty quickly. So the guy who answered "seven" when asked how happy he was a decade ago while a student without much money may well answer "seven" when asked again today because he can still imagine being even happier - who can't? Alternatively, imagine if we stopped measuring folks' income directly and started asking, as one Twitterer [update: Tim Harford, thanks for the reminder, LemmusLemmus] suggested a while back, how rich people felt on a scale from zero to ten: "Oh, I just got paid today, so I'll say a 7."

But suppose that we take the happiness directive seriously. What policy implications flow from this kind of work:

Here we explore the extent to which baseline happiness is influenced by genetic variation. Using data from Add Health, we employ a twin study design to show that genetic variation explains about 33% of the variation in happiness, and that the influence of genes varies by gender (women 26%, men 39%) and tends to rise with age. We also present evidence that variation in a specific gene predicts happiness. Individuals with a transcriptionally more efficient version of the serotonin transporter gene (SLC6A4) are significantly more likely to report higher levels of life satisfaction; having one or two alleles of the more efficient type raises the average likelihood of being very satisfied with one's life by 8.5% and 17.3%, respectively. Finally, using data from an independent source (the Framingham Heart Study) we show that a linked single nucleotide polymorphism (rs2020933) in the SLC6A4 gene also predicts life satisfaction. These results are the first to identify a specific gene that may be associated with baseline levels of happiness.

The policy conclusion seems obvious to me: provide a baby subsidy to folks with the transcriptionally efficient alleles. Make the magnitudes big enough to matter. Within a few generations, we have an expectationally happier population. Look again at the magnitude of the differences reported: they're big relative to the effects of other shocks, and they're baseline rather than transitory. If what we care about is national happiness, it's hard to think of anything that would be more effective. Now, I wouldn't advocate the policy. But neither would I advocate the other policies that get pushed by the happy people.

The excellent James Fowler is one of the authors of the paper and sensibly avoids policy conclusions. He instead makes even more interesting suggestions about using genes as instruments in disentangling endogeneity problems.