Sibling rivalry: When the fighting crosses the line

Sibling rivalry. Every parent and every sibling understands what this means. Siblings fight. A lot. And sometimes those fights escalate to involve physical, verbal, and psychological aggression. Aggression between siblings is so common that people often believe that these behaviors are part of the normal process of growing up, but recent research shows us that sibling aggression can cross the line and parents need to know when to seek help. How often preschoolers target their sibling aggressively may provide an important clue, suggests a recent study in the Journal of Child Psychology and Psychiatry.

Sibling conflicts are common, especially during the preschool years, and these experiences help children learn important skills such as understanding another person's perspective. However, when parents report that one sibling is targeting their brother or sister aggressively most days of the week, this may be an indication of a more serious behavioural problem.

"How do parents know if they are raising a typical 'threenager' who will show increasing self-control with age, or if the aggressive behaviours they are seeing indicate a significant problem that will escalate if left untreated?" asks Melanie Dirks from McGill University's Department of Psychology, the lead author of the study. To help answer this question, she and her co-authors analyzed data from over 1,500 parents on how often their preschool-aged children engage in aggressive and other problem behaviours.

Daily aggression toward a sibling may signal potential behavioural problems

Professor Dirks found that behaviours like hitting a sibling, calling a sibling names, and leaving a sibling out of play, were only atypical when parents reported that they happened most days. "Very frequent aggression towards a sibling may be an indicator that the child is experiencing significant emotional or behavioural problems that will worsen if left untreated," explains Dirks. These behaviours are much more modifiable at young ages, before they become entrenched.

There are solutions for parents who see this type of behaviour in their child. Dirks says, "Parents who are concerned about their children's aggression – toward siblings or others – should seek out a clinician who will provide a thorough assessment and then help them to learn developmentally appropriate behavioural management techniques." Although it may be tempting to separate siblings who are fighting a lot, Dirks notes that interacting with brothers and sisters promotes healthy development in many ways. For this reason, it is important to help siblings learn how to play together in a positive way and how to resolve their conflicts constructively.

Data were obtained from the Multidimensional Assessment of Preschoolers Study (MAPS), a National Institute of Mental Health study led by Northwestern University's Lauren Wakschlag.