MAOA-uVNTR genotype predicts interindividual differences in experimental aggressiveness as a function of the degree of provocation

•MAOA-uVNTR-genotype is associated with reactive impulsive experimental aggressiveness.•The association is not modulated by sex.•The association increases in a fashion linear to the degree of provocation.•The MAOA-uVNTR low-functional alleles are not associated with increased aggressiveness per se.•Rather, they are associated with increased aggressive reactivity to provocation. The MAOA-uVNTR has been suggested to play a role regarding aggression, however, results are inconsistent. We aimed at further elucidating potential effects of the MAOA-uVNTR on aggressiveness with respect to potential modulators: sex, experimental vs. trait aggressiveness and type of aggressiveness (proactive vs. reactive aggressiveness). We tested 239 healthy young adults (88 men/151 women). Participants were genotyped for the MAOA-uVNTR and performed a modified version of a competitive reaction time task – a commonly used and well established tool to elicit and measure aggressiveness. Furthermore, they completed a self-report scale measuring trait aggressiveness. We found a main effect of MAOA-uVNTR on a measure of reactive aggressiveness for both men and women, whereby the low-activity alleles of the MAOA-uVNTR were associated with substantially increased aggressive reactions (p