It was always expected that the rates of aggression and delinquency would increase among the boys, while girls were considered somewhat protected. However, a new study shows that the differences between girls and boys are diminishing and that middle school girls are displaying more delinquency and aggression than their male classmates.

The possibility of girls committing a delinquent act such as hitting or shoving someone, throwing objects at cars and people, and stealing are raising among the sixth and seventh grades pupils.

Scientists are suspecting hormonal changes to be responsible for a change in their behaviour. Girls' entry into adolescence is generally thought of as a vulnerable time for depression, and studies tend to focus on girls' emotional experiences with sadness and depressed moods. However, the study showed an increase in a different negative emotional experience – anger.