"In a healthy environment, increased threat sensitivity, poor emotion control and enhanced fear memory in MAOA-L [i.e., the "warrior" variant] men might only manifest as variation in temperament within a 'normal' or subclinical range. However, these same characteristics in an abusive childhood environment--one typified by persistent uncertainty, unpredictable threat, poor behavioral modeling and social referencing, and inconsistent reinforcement for prosocial decision making--might predispose toward frank aggression and impulsive violence in the adult."