We elected to study allelic variation in 5-HTTLPR, a polymorphism in the serotonin transporter promoter gene area (SLC6A4), because Taylor et al.31 examined 5-HTTLPR in the only study showing full differential susceptibility. Also, considerable prior GxE research has investigated adverse environmental influences interacting with the 5-HTTLPR for many psychiatric outcomes.32, 33, 34, 35 We chose to assess parenting behavior, specifically the range from non-supportive to positive/supportive parenting, as the environmental context given extensive research documenting associations with youths' positive affect and overall social-emotional functioning.14, 15
