The finding of a consistent mechanism of G-E interplay across the different environmental risk factors suggests a general mechanism of environmental influence on EXT regardless of the particular manifestation of the environmental risk. The consistency is especially noteworthy given the differences in content of the environmental measures, the use of multiple informants and methods of assessment, and the differences in heritability. Also, the nature of the G × E interaction with EXT was the same regardless of whether the environmental variable conferred distal risk (independent life events), or risk that was proximal and malleable (peers, parent-child relationships, academic achievement and engagement), the latter being theorized to be most relevant to G-E processes2,5. Additionally, while all the environmental variables were correlated, the moderation effects were not solely due to the effect of a general environmental risk factor. Finally, our results are consistent with several previous studies that have examined single externalizing phenotypes (e.g., conduct problems, alcohol use, smoking) and environmental moderators (e.g., peers, social and demographic variables)5,6,22,35-37,64,65. Integrating our results with the broader literature then suggests a general principle of G-E
