It's a well-documented fact that children from zero to two can be spontaneously aggressive and that boys can be among the worse culprits. Even after being socialized, seven percent of boys will continue to be hyper-aggressive until the age of nine.

Women who smoke during pregnancy risk delivering aggressive kids according to a new Canada-Netherlands study published in the journal Development and Psychopathology.

Aren't you ashamed of yourself? All these years, you've been trying to build up your child's self-esteem, and now a growing body of research suggests you may be making a big mistake.

Preschoolers who are aggressive, angry, and inattentive tend to have fewer playmates than their non-aggressive classmates, whether they are boys or girls. In comparison, non-aggressive children do better at interactions with many peers over time.

Students who bully others tend to have difficulties with other relationships, such as those with friends and parents. Targeting those relationships, as well as the problems children who bully have with aggression and morality, may offer ideas for intervention and prevention.

Physical aggression in children comes from their genes and the environment in which they grow up. Social aggression, such as spreading rumors or ignoring other children, has less to do with genetic factors and more with environmental factors.

Among children of mothers with low education levels, those who receive regular care from other adults during preschool years may be less likely to have problems with physical aggression, according to a report in the November issue of Archives of General Psychiatry, one of the JAMA/Archives journals.