Happiness is being Danish, it seems.
Eugenio Proto and Andrew Oswald find that Danes are happier than other people, that Danes living in the United States are happier than other ethnicities in the United States, and that Danes are less likely to have the short-allele variant of 5-HTTLPR, which is associated with depression and mental disorder.
There's a lot of risk of "just-so" findings in genetic correlates: you've rather a few alleles, so some of them will come up significant in studies just by chance. But Proto and Oswald weren't out on a data-mining expedition here. They started with the usual result that Denmark is one of the happiest countries in world survey rankings of such things, then looked to the psych lit to find genes correlated with depression, then checked whether Danes are less likely to have that variant. And, the "Danes in the United States are happier too" finding weighs against other potential explanations, like that perhaps it's Danish welfare systems driving things rather than characteristics specific to Danes.
Further, the greater your "genetic distance" from the Danes, the worse your country's happiness score.
If this one holds up, I wonder what happens to the literature that argues the happiness merits of Nordic social democracy. I suppose you'd need a rich international panel checking the interaction between Danish background and the country of residence's institutional structure. I wonder whether the Danish diaspora would be big enough for reasonable tests.
HT: Chris Dillow