in tackling aggression, the work of Richard Tremblay in Nature News Feature Behaviour and Biology: The Accidental Epigeneticist "This and later work culminated in Tremblay's 'original sin' hypothesis: that physical aggression is the default setting in human behaviour5. It peaks between the ages of two and four, and is usually socialized out of children by the time they enter school (see 'Aggression regression'). “We took the view that violence, and physical aggression, is a part of us as a species,” says Nagin, “so the issue is not how we learn it, but rather how we learn to control it.”
Many criminologists dismissed the findings. They argued not that the idea was wrong, but that it was irrelevant — that chronic childhood aggression is trivial compared with murder and rape in adulthood, and that the former does not explain the latter. Most still focus primarily on delinquency during adolescence, and for good reason, says sociologist Robert Sampson at Harvard University in Cambridge, Massachusetts. “Early childhood is centrally important, but it's not determinative, because there are still changes [in behaviour] later on.”
Yet the Montreal and similar longitudinal studies show that heightened physical aggression at a young age correlates with serious antisocial behaviour in adolescence and adulthood, says Tremblay. He is fond of citing the view that Saint Augustine offered some 1,600 years ago: “It is not the infant's will that is harmless,” he wrote, “but the weakness of infant limbs.”"