Why Individual Prediction Doesn’t Scale to Group Differences in Polygenic Scores: Debunking a Common Fallacy

I’m starting to get tired of answering the same objections to polygenic scores (PGS) again and again, so I want to deal with one especially obnoxious criticism here once and for all (hopefully). A recurring misunderstanding in online debates is the claim that a PGS with low individual-level predictive power (say, R² = 0.02) can’t possibly tell us anythi…