No Evidence for Social Genetic Effects or Genetic Similarity Among Friends Beyond that Due to Population Stratification: A Reappraisal of Domingue et al (2018)
Using data from 5500 adolescents from the National Longitudinal Study of Adolescent to Adult Health, Domingue et al. (Proc Natl Acad Sci 25:256., 2018) claimed to show that friends are genetically more similar to one another than randomly selected peers, beyond the confounding effects of population stratification by ancestry. The authors also claimed to show ‘social-genetic’ effects, whereby individuals’ educational attainment (EA) is influenced by their friends’ genes. We argue that neither claim is justified by the data. Mathematically we show that (1) the genetic similarity reported between friends is far larger than theoretically possible if it was caused by phenotypic assortment as the authors claim; uncontrolled population stratification is a likely reason for the genetic similarity they observed, and (2) significant association between individuals’ EA and their friends’ polygenic scores for EA is a necessary consequence of EA similarity among friends, and does not provide evidence for social-genetic effects. Going forward, we urge caution in the analysis and interpretation of data at the intersection of human genetics and the social sciences.
KeywordsGenomic similarity Social-genetic effects Confound Kinship
This research was supported by the Australian Research Council (DP160102400; FT160100298; FL180100072), the Australian National Health and Medical Research Council (1113400 and 1078037) and the National Institute of Health (NIH Grants R01AH042568 and R01MH100141). K.J.H.V. is supported by the Foundation Volksbond Rotterdam.
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Conflict of interest
The authors declare that they have no conflictof interest.
Human and Animal Rights and Informed Consent
This articledoes not contain any studies with human or animal subjects performed by the any of the authors.
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