Marek Szewczyk

“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.”
― Robert M. Sapolsky, Behave: The Biology of Humans at Our Best and Worst