genetic effects, versus specific genes in a complex polygenic system. The field of genetics has moved toward creating polygene scores that aggregate across many genes and show predictive power in cases where individual genes cannot be detected (Purcell et al. 2009). Moving studies of measured gene–environment interaction in this direction, to encompass aggregate genetic risk, may be one way to improve replicability of effects and to enhance cross-fertilization between quantitative and molecular genetic research.
