What is the Line: When Does Sibling Conflict, Teasing, and Roughhousing Become Something More Serious? (SAARA Bulletin #4)

Corinna Jenkins Tucker, Tanya Rouleau Whitworth, and David Finkelhor
Fall 2023

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It can be challenging to know when siblings’ behaviors cross the line to something more troubling. During conflict and play, aggressive behaviors like biting, pushing, making threats, or using intimidation, are common and often considered normal between siblings. Parents and professionals who work with children often mislabel aggressive sibling behaviors as "just" rivalry. These same aggressive behaviors are typically condemned when they occur between friends, classmates, or romantic partners.

There are no universally accepted criteria regarding sibling aggression, making it difficult to know when to be concerned, intervene in sibling interactions, or seek help. However, it is critical to recognize aggressive and abusive behaviors between siblings because their negative effects on well-being are similar to the impacts of parental child maltreatment and intimate partner violence. This bulletin provides guidance on identifying when sibling behavior has crossed the line.1

Aggressive Behaviors in Children: Normal but Not Okay Towards a Sibling

Sibling conflict is an expected experience of growing up and being part of a family with multiple children. Most sibling conflicts are mild in nature and brief, including incidents of teasing, yelling, and bickering over things said or shared space.

During sibling conflict, younger children may have aggressive outbursts such as screaming, biting, hitting, kicking, and throwing objects. Such behaviors may continue throughout childhood, but usually decrease. As children age, social aggression towards others develops with increased verbal skills and number of social relationships.

Two young sisters sitting on a couch with their backs to each other, both looking angry.

The fact that displays of aggression are considered a normal part of development does not mean sibling-directed aggression is okay. Aggression between siblings can have negative long-term impacts on mental and physical health and interpersonal relationships (see SAARA Bulletin #1).

Central to distinguishing acceptable from harmful sibling behaviors are: (1) intent to harm,2 and (2) impact on one or both children (e.g., feeling mistreated or hurt). When aggressive behavior occurs, parents should stop it immediately and take steps to prevent further harm (see SAARA Bulletin #2).

Because conflict between siblings is almost inevitable, the goal within families should be helping children learn emotion regulation and social skills to foster constructive rather than destructive forms of conflict. Understanding the differences between these two forms of conflict can help illuminate the line when sibling interactions become potentially harmful.

Constructive Sibling Conflict

Conflict can provide important learning opportunities to develop socio-emotional skills and strengthen interpersonal relationships. Sibling conflicts with these types of benefits are called constructive conflicts. Parents can help their children engage in constructive conflict behaviors, like listening, seeing another person’s perspective, and learning to compromise.

When siblings develop these important socio-emotional skills, they often come to an agreement on the issue to be solved and work together to find a mutually satisfying solution. Acquiring these important relationship skills is helpful for future conflicts with siblings and others, like peers and romantic partners.

Destructive Sibling Conflict

Destructive sibling conflict is characterized by intense emotions that escalate, may include physical, property, and psychological aggression, and is unlikely to be resolved in a mutually acceptable way. Behaviors displayed during destructive conflict are often intended to hurt and may be mutual. However, mutual sibling aggression does not mean the exchange is harmless.

Aggressive behaviors children use during destructive conflict may be mild or severe. Mild aggression does not leave an injury or include the use of weapons or weapon-like objects. Examples of mild aggression include pushing, grabbing, insulting, hitting, and breaking belongings. While mild aggression does not cause a physical injury, it may cause emotional harm, especially if it persists or escalates over time.

Severe aggressive behaviors do leave a physical or emotional injury and can involve the use of a weapon or weapon-like object. Incidences of severe aggression include kicking, punching, beating, repeatedly calling a sibling dumb, ugly, or unloved, or threatening significant harm. Such behaviors usually peak during adolescence.

Sibling Abuse

A woman is trying to comfort her distressed teenage daughter.

Sibling abuse occurs when individual incidents or patterns of behavior between siblings pose a high risk of serious physical and/or emotional harm. These behaviors tend to be one-sided, with one child consistently harmed due to a power differential between the siblings based on age, gender, physical size, cognitive ability, parental favoritism, or some other factor.

Sibling abuse usually has one or more aggravating elements, such as repetition (happening multiple times), persistence (happening over a period of time), and the inclusion of others (like another sibling, a friend, or a parent).

Behaviors that may occur in abusive sibling relationships include violence that results in a serious injury (e.g., a broken bone or black eye) or is life-threatening (e.g., strangulation), as well as extreme threats of harm or intimidation (e.g., threatening to kill a sibling, intentional destruction of cherished items, a reign of terror). A psychologically abused sibling may face demeaning behavior, humiliation, alienation, blackmail, or acts of revenge.

Difficulty in Recognizing Sibling Aggression

It can be difficult to know if a child has been harmed by their sibling’s behavior. Relying on a sibling’s or parent’s perception of whether harm has been done can be ineffective. Parents and siblings often make excuses or justifications for aggressive and abusive sibling behavior. When aggression is normalized in a family (and in society), sometimes the victimized sibling also struggles to identify the harm.

Additionally, many siblings are characterized as being both the bully and the harmed child. An unclear power differential can lead to greater acceptance of aggressive sibling behavior. In these cases, the aggression could be tolerated because it is between "equals" or because the behaviors "seem fair."

Despite these barriers to recognition, research on the harmfulness of sibling aggression and abuse is clear, making it important that these behaviors be taken just as seriously when they occur between siblings as in other relationships.

The following guiding questions3 can help identify harmful sibling aggression or abuse. Note that not all questions have to be answered with a "yes" for the behavior to be harmful. Also, being viewed as common or normal between siblings does not make a behavior harmless.

Guiding questions:

  • Is physical violence (e.g., hitting, kicking, shoving) occurring after the toddler years?
  • Are sibling conflicts consistently settled by one sibling "winning" the fight?
  • Is it physically or emotionally harmful or is there a serious risk of harm?
  • Is the behavior planned or patterned, suggesting an intent to harm?
  • Does a sibling feel victimized, targeted, or afraid?
  • Has it escalated over time?
  • Is there a power differential between the siblings?

For further reading:

Caffaro, J. V. (2014) Sibling abuse trauma: Assessment and intervention strategies for children, families, and adults (2nd edition). Routledge.
Rypi, A. (2023) Ambiguous but crucial boundaries - Professionals differentiating sibling abuse from sibling quarrels Sociological Focus, 56(2), 209-225. https://doi.org/10/grwd36
Tucker, C. J. & Finkelhor, D. (2017). The state of interventions for sibling conflict and aggression: A systematic review. Trauma, Violence, & Abuse, 18(4), 396-406. https://doi.org/10/gbwz64
Tucker, C. J., Finkelhor, D., & Turner, H. (2023). Patterns of sibling aggression and mental health in childhood and adolescence. Journal of Family Trauma, Child Custody & Child Development. https://doi.org/10/kk44
Wiehe, V. R. (1997). Sibling abuse: Hidden physical, emotional, and sexual trauma (2nd edition). Sage Publications, Inc.


1This bulletin focuses on physical, psychological, and property sibling aggression and abuse. Sibling sexual abuse involves somewhat different dynamics and is covered in a separate SAARA Bulletin.
2Accidents do not include an intent to harm.
3These questions were adapted from Caffaro (2014) and Wiehe (1997).