this nature are challenging in studies of cannabis exposure. First, no genomic variants have been robustly and causally implicated in the etiology of early cannabis use (or any cannabis-related measure for that matter)(104; 105). Secondly, those that have been studied are likely to relate to cannabis as much as they do to putative confounders (e.g. CNR1 variation is associated with cannabis exposure but also with alcohol involvement, a putative confounder (106)).
