With the exception of the ADH1B variants rs1229984 and rs2066702 (the analogous variant in individuals of African genetic ancestry), which show relatively large effect sizes for AUD and other alcohol‐related phenotypes, 99 common genetic variants affecting liability for AUD typically demonstrate very small effect sizes. This is consistent with genetic findings for other psychiatric disorders: in fact, the high degree of polygenicity underlying all psychiatric disorders, complex traits and phenotypes that COGA investigates is well‐documented. 107 , 108 Polygenicity refers to the small and incrementally additive effects of common variants across the genome. 109 An ongoing debate in the field of complex trait genetics concerns the concept of “missing heritability” (the difference between h 2 family, the heritability estimated using twin and family studies, and h 2 GWAS, the heritability estimated from genetic variants known from GWAS to be robustly associated with a phenotype), along with the “hidden heritability” (the difference between heritability estimated using all the SNPs on a genotyping chip, known as h 2 SNP, and h 2 GWAS) and “still‐missing heritability” (the difference between h 2 family
