Including SOB in genotypic models yielded two new significant findings not previously observed. One was an interaction effect between genotype and SOB. This interaction between SOB and DRD4 in predicting venturesomeness (EIQ-V) is consistent with our hypothesis that dopamine D4 receptors may be particularly mechanistically entangled with SOB effects. Such an interaction may indicate that both SOB and DRD4 act through related dopaminergic substrates. Additionally, the DRD2 by DRD4 association revealed when SOB was included in models together with DRD2 and DRD4 tentatively suggest that SOB and dopamine polymorphisms control overlapping traits. This DRD2×DRD4 associations with sensation seeking (SSS-Total) is consistent with past findings of an interaction between DRD2 and DRD4 on impulsivity, where similarly the most extreme impulsive individuals were A1+/L+ [54].
