We’ve known for quite a while that there is probably interaction between nature & nurture when it comes to intelligence (check e.g. the Flynn-effect, the influence of scarcity,…). This article on Citylab discusses a new study that confirms an insight from an earlier study that there is a difference between the influence of nature and environment depending on the socio-economic background. But there is an unexpected twist… it’s only found in the US:

But a strong new analysis published in the journalPsychological Science suggests that the role of genetics in intelligence indeed varies with socioeconomic status—at least in the United States. The data reveal no such pattern in other parts of the developed world, a finding the researchers attribute to “more uniform access” to social programs such as strong education and health care.

“The differences observed across nations might be explained by weaker social safety nets in the U.S. compared to Western Europe and Australia,” the psychologist Elliot Tucker-Drob of the University of Texas at Austin, the paper’s lead author, tells CityLab via email. “While this study did not investigate specific policies or services that might explain the differences … I think that it is fair to say that the causes of the difference are likely to be manifold.”

And if we say robust, it’s because of the magnitude of the study, it’s a meta-study using nearly 25000 pairs of twin and siblings from 8 studies (2 in the US, 6 outside).

Abstract of the study:

A core hypothesis in developmental theory predicts that genetic influences on intelligence and academic achievement are suppressed under conditions of socioeconomic privation and more fully realized under conditions of socioeconomic advantage: a Gene × Childhood Socioeconomic Status (SES) interaction. Tests of this hypothesis have produced apparently inconsistent results. We performed a meta-analysis of tests of Gene × SES interaction on intelligence and academic-achievement test scores, allowing for stratification by nation (United States vs. non–United States), and we conducted rigorous tests for publication bias and between-studies heterogeneity. In U.S. studies, we found clear support for moderately sized Gene × SES effects. In studies from Western Europe and Australia, where social policies ensure more uniform access to high-quality education and health care, Gene × SES effects were zero or reversed.