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Accompanying the latest round of results from genome-wide association studies (GWAS) and the increasing use of polygenic scores—indices of genomic variants used to predict phenotypic values—to predict phenotypic outcomes is an unshelving of hereditarian prescriptions for society calling for interventions ranging from hailing the prospect of genetic testing for use in school tracking (Plomin 2018) to outright eugenical measures (Hsu 2014). Enthusiasm for the application of heritability estimates and polygenic scores to problems in social sciences has spilled over into the academic dark web and more extreme hereditarian sources who seek to apply them to find proof of immutable genetic causes of presumed racial and class differences in a variety of cognitive and behavioral features.
While outright denial that genetic influences on behavior are possible has faded, two other problematic arguments are used in anti-hereditarian replies to hereditarianism in social media and the academic literature. One is characterized by highlighting the complexity of behavior in the context of the general failure of behavior genetics to yield convincing associations between genes and features of behavior or cognition. This complexity argument is used both to characterize genetic accounts of behavior as inadequate in their simplicity and to suggest that the evolution of behavioral characteristics will be constrained by genetic complexity in ways other aspects of phenotype will not. The other argument is based on claims of how dissatisfying explanations of genetic effects are in the absence of clear mechanistic links between genome and phenotype. In this view, genuine genetic explanation requires an account of traits specifically linking gene to protein to biological process to end phenotypic outcome.
Here, I argue that both the complexity argument and the insistence on molecular explanation do not do the kind of work anti-hereditarians would like them to do. While human behavior and cognition are doubtlessly complex, the complexity argument corners anti-hereditarians in both theoretical and empirical ways. The insistence on molecular explanation is a needlessly reductionist move that risks casting genetics in a deterministic light. In both cases, these arguments are superfluous to the core of the classic, and correct, anti-hereditarian argument that emphasizes the context dependency of genetic and environmental effects.
Some Responses to Recent Hereditarian Work
I focus on two anti-hereditarian responses to claims about the genetics of behavior...