It is known that children whose parents fight a lot tend to develop emotional problems later in life. But, when could you start expecting a child in an unhappy family to start showing signs of aggressive behavior? It turns out signs of aggression can be seen in children young as the age of three.

The researchers also say that aggressive behavior may signal the possibility of maltreatment at home. Previous studies have shown that parental marital conflict increases the risk of injuries among children.

“Considering that many social problems have their roots in family experiences, scholars have become interested in exploring potential family factors – including marital conflict – that are correlated with young children’s aggression,” said the study’s lead author, Hyun-Sim Doh, a professor in the department of child development in the College of Social Science at Ewha Womans University.

The study included 340 children below the age of three as well as their mothers and teachers at 20 day care centers in Korea.

“Although the study involved children and their families in Korea, the findings could be relevant to children and their families in the U.S. and other countries because child maltreatment and family violence are worldwide social problems," Hyun-Sim Doh said.

All the children in the study group displayed signs of aggression like punching other kids, bullying and breaking things.

The intensity of a child's aggressive behavior was associated with the severity of marital conflict. Mothers who were facing problems in the marriage were more likely to report that they neglected their child. Also, they were more likely to report that they either physically or psychologically abuse the child.

“It’s important for practitioners to focus on aggressive behavior at an early developmental stage as young children are likely to be more responsive to primary prevention,” Jun Sung Hong, a doctoral candidate in the School of Social Work at the University of Illinois at Urbana-Champaign said.

There are other studies that say that not all children who grow up seeing their parents fight become aggressive and anti-social. Individual differences also make some children at risk of developing this kind of violent behavior.

The study was published in Children and Youth Services Review.