They found that “the greater a nation’s genetic difference from Denmark, the lower is the reported well-being of that nation (that is, the greater their population’s level of struggling).” Countries with the least genetic similarity to Denmark, including Ghana and Madagascar, are “particularly unhappy,” they write.

What’s more, they report this correlation remains robust after taking into consideration an array of factors, including a nation’s economic vitality (as measured by its gross domestic product), the generosity of its welfare benefits, and a range of cultural and religious variables…

They found “an unexplained positive correlation between the happiness today of Country X, and the observed happiness of Americans whose ancestors come from Country X.” This finding, they note, is “consistent with the existence of an underlying genetic component in international well-being patterns.”