For some parents, their child's first aggressive act is as unsettling for them as for the playmate or sibling who just got whacked in the head with a sippy cup. It can trigger shock and dismay: "I can't believe Aiden just hit Abby!"—as well as suspicion and guilt: "Where could he have possibly learned that?"
According to recent studies in early childhood aggression, however, the most important question that parents can ask themselves is "How should we respond?" Since the 1960s, aggressive behavior in young children was thought to be acquired mainly through observation and imitation. Childhood roughhousing was therefore often discouraged because parents saw it as a behavioral precursor to hostility.
However, research over the last ten years has shown that aggression emerges naturally in children and diminishes as they learn how to express themselves appropriately. As psychologist Kate Keenan states in an article on the Excellence-earlychildhood.ca website, "One could argue that the reason most children do not develop problems with aggression is because they are presented with opportunities to experience intense negative emotions as infants, engage in aggression as toddlers, and are discouraged in various ways from repeating unacceptable behavior." This means that the initial behavioral changes most beneficial to an aggressive toddler must be made by the parents themselves.
The Difference between Young Girls and Boys
In other words, Aiden needs his parents to teach him how physical play is different from aggression. While girls and boys are equally aggressive as toddlers, boys soon become more prone to physical aggression. In one study Keenan cites, three-year-old boys demonstrated twice as many hostile behaviors as girls.
Psychologist Steve Biddulph, author of Raising Boys, mentions several differences between the genders that suggest why rough-and-tumble play is necessary in the development of male children. Biologically, at around age four, boys experience an upward spike in testosterone levels for around a year. During this time they become interested in "action, heroics, adventures and vigorous play" and will thus need to be taught how to keep their sudden outpouring of playful aggression within the limits of fun.
However, this biological component doesn't explain why boys at age three would demonstrate more aggression than girls. It could be the result of how boys and girls are treated differently socially, even at a very young age. For example, Biddulph notes that adults typically discipline boys more harshly, with mothers tending to hit boys harder and more often than they hit girls. He also mentions research showing that parents cuddle girl children much more, even as newborns, and that boy babies are spoken to less frequently.