When Does Sibling Fighting Become Harmful?

Two young brothers standing in front of a pond.

Source: Vitolda Klein/Unsplash

Numerous studies show that sibling relationship quality is important for well-being and relationship experiences with others, even in adulthood. Currently, society’s notions of typical sibling behaviors include a vague and wide range of behaviors, leaving parents and practitioners often confused about whether behaviors between brothers and sisters have gone too far. As a result, harmful sibling behaviors, even abuse, often go unrecognized and are commonly dismissed as sibling rivalry.

Sibling Aggression

Unlike rivalry, aggressive sibling behaviors, including emotional, physical, and property aggression, are motivated by a desire to cause harm and suffering. Displays of emotional aggression include humiliation, threats, and intimidation. Causing physical pain through purposefully hitting, pinching, kicking, and beating are examples of physical aggression. Some examples of property aggression are forcible taking, theft, and destruction of personal items. It is important to note that sibling aggression may occur regardless of whether siblings are rivalrous.

Aggressive behaviors can leave a sibling feeling mistreated and should be stopped immediately. If parents or caregivers do not intervene to stop sibling aggression, it may escalate to become more severe over time. A parent’s failure to intervene may also be experienced as a second victimization by the harmed child. Research shows that aggressive sibling behavior negatively impacts mental and physical health and social relationships, including an increased risk for depression and peer bullying.

It is common for siblings to share or alternate the roles of aggressor and victim. It is essential to avoid mistaking this mutuality for harmlessness. Whether the aggression is mutual or experienced as either an aggressor or a victim, both siblings’ well-being and the quality of their relationship suffer. Sometimes, the impact of the behavior is not the same for each sibling.

Sibling Abuse

Abuse of a child is commonly associated with adult parents or caregivers. However, although difficult to imagine, sometimes a sibling is consistently the one who intentionally harms a child in the family and causes serious physical or emotional harm. When abuse happens, it likely reflects a power difference between the siblings in terms of physical size, cognitive ability, gender, age, or role in the family (e.g., an older sibling acting as a caregiver).

Other characteristics of sibling abuse include that it is often chronic, intense, and long-standing, but a severe one-time event may also be abuse. A sibling may make threats of harm, cause a serious injury, engage in blackmail, involve a brother or sister in criminal or self-harming behavior, expose their sibling to pornography, or commit sexual assault. In families where sibling abuse occurs, the harmed sibling may repeat the behavior with other children in the family.

An important marker for distinguishing between aggressive and abusive sibling behavior is the enduring emotional impact on the harmed child that often reflects their feeling of powerlessness. They may feel hopeless, fearful, and distressed and act overly deferential to their sibling. The harmed child may also avoid their sibling as best they can, including staying away from home. Sometimes, siblings do not realize aggressive or abusive behaviors are harmful until later in life, which may lead to estrangement from their families in adulthood.

Parents and practitioners must be mindful of the nature of siblings’ interactions and be careful not to reinforce aggressive and harmful behavior or dismiss it as rivalry. This is especially important given that some children may not realize what is happening or make excuses for the behaviors.

Aggressive behavior may be addressed through mediation techniques or time out, which have both been shown to reduce sibling aggression. In the case of abuse, outside help is likely needed from pediatricians, therapists, or family resource centers, who can offer resources and family-based intervention options.

Sibling relationships are one of the longest-lasting relationships a person can have. They shape our ways of relating to others, managing our emotions, and resolving conflicts—for better or for worse. Increasing awareness of sibling aggression and abuse is critical, given their negative impacts on mental, physical, and relationship health across the lifespan. Shaping a safe and, possibly, warm lifelong relationship with a brother or sister begins in childhood.