Tanya Rouleau Whitworth, Corinna Jenkins Tucker, Lizzie Martell, and David Finkelhor
Summer 2024
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The goal of this bulletin is to define sibling sexual abuse (SSA) and provide guidance for parents and professionals on how to respond. Our definition of SSA includes the behaviors engaged in, the motivation of the child who caused harm, and the impact (or likely future impact) on the child who was harmed.
Current estimates suggest that 2-5% of children and adolescents experience sexual abuse by a sibling. SSA typically begins earlier and lasts longer than other types of child sexual abuse; the average age of the harmed child at the onset is 8 years. Importantly, research shows that the impact of SSA on mental health and interpersonal functioning can be just as severe as sexual abuse by an adult caregiver.
Defining SSA
There is no simple guideline for determining whether sexual behavior between siblings is abusive. Some definitions of SSA, particularly legal definitions, specify an age gap of more than 4 or 5 years. However, research with survivors shows that sibling sexual behavior can be experienced as abusive even when siblings are much closer in age. Gender is certainly a factor—the most common scenario is an older brother and a younger sister—but SSA can occur with any combination of sibling genders.
Peter Yates and Stuart Allardyce, leading experts in this field, put forward a continuum of sibling sexual behavior with four levels: (1) developmentally appropriate, (2) inappropriate, (3) problematic, and (4) abusive. This is a useful tool for conceptualizing the behavior of the child who has caused harm; however, the label assigned may not correspond to the amount of trauma experienced by the harmed child.
Drawing from this continuum and the extensive work of John Caffaro in this field, we developed the following list of characteristics that can be signs of SSA. Any one of these signs is cause for concern:
- Sexual behaviors that involve physical contact, like fondling, oral-genital contact, or intercourse
- Non-contact behaviors that are not age-appropriate, like the production and sharing of sexual images or spying on a sibling while undressed
- Sexual behavior in the context of a power differential based on age, gender, cognitive or physical ability, social competence, family role (e.g., caregiver), or parental favoritism
- Sexual behavior involving the use of aggression, force, coercion, trickery, bribes, or misrepresentation
- Sexual behavior motivated by an intent to harm, dominate, or humiliate, or by compulsion or pressure from others
- Child feeling ashamed, fearful, angry, anxious, or showing other signs of trauma in the wake of a sexual interaction
Experts do say that sometimes siblings engage in what may be developmentally appropriate sexual exploration. In this case, all of the following signs must be present:
- Occasional and of brief duration (frequency confirmed, not assumed)
- Occurs between children with similar levels of development
- Motivated by curiosity that makes sense for the children’s ages
- Playful (without coercion or deception)
- Only minor embarrassment if discovered
- Children are easily redirected by parents or caregivers
Even when sibling sexual behavior meets these criteria, caregivers should redirect the children and use it as a teaching moment about healthy and safe body boundaries. Any sexual behaviors between siblings that don’t meet this description deserve careful investigation by a qualified professional. Families and children can seek help from a pediatrician, mental health clinician, school nurse, or local family resource center.
SSA should be taken as seriously as other forms of child sexual abuse. Professionals responding to sibling sexual behavior may find their training on child sexual abuse and maltreatment to be helpful; however, keep in mind that there are unique dynamics in sibling relationships that are important to consider, like birth order, shared living space, and children’s family roles. The field of SSA intervention is evolving and should be consistently included in continuing education for professionals in a variety of fields.
Discovery and Response to SSA
Research shows that children are unlikely to tell anyone about SSA. Often children are secretive because they feel complicit and confused about their experiences. Sometimes sibling sexual behavior starts out as exploratory and mutual but becomes coercive when one child wants to stop. Other times, siblings become sexually involved to fill needs for closeness not being met by caregivers. Even in cases involving clear coercion or force, the harmed child often blames themself and mistakenly thinks they could have stopped it somehow.
Parents who become aware of sibling sexual behavior may dismiss it as “normal curiosity” and harmless. Other parents may panic, assuming the worst. They may punish and shame the children. Neither reaction is helpful to the children. It is important to believe children who say they have been harmed by a sibling and seek out professional help if any signs of abuse are present. Learning to identify harmful sibling dynamics and signs of child sexual abuse will contribute to early intervention for sibling sexual trauma and its associated secrecy and shame.
A whole-family, child-centered, comprehensive response is necessary when SSA has occurred. There may be a need to address dysfunctional family dynamics and parenting practices and provide psychoeducation to all family members on healthy relationships and sexuality. The harmed child should be assessed and treated for trauma symptoms and misunderstandings about sexual behavior or culpability. Interventions with the child who caused harm should be trauma-informed and strengths-based. Most children and adolescents who display harmful sexual behaviors will not become adult sex offenders; evidence-based treatment can help ensure this.
For further reading:
Bertele, N., & Talmon, A. (2023). Sibling sexual abuse: A review of empirical studies in the field. Trauma, Violence, & Abuse, 24(2), 420–428. https://doi.org/10/grw7r9
Caffaro, J. V. (2014). Sibling abuse trauma: Assessment and intervention strategies for children, families, and adults (2nd edition). Routledge.
Caffaro, J. (2021). Sexual abuse of siblings. In T. K. Shackelford (Ed.), The SAGE Handbook of Domestic Violence (pp. 758–778). SAGE Publications Ltd. https://doi.org/10.4135/9781529742343
McCoy, K., Sonnen, E., Mii, A. E., Huit, T. Z., Meidlinger, K., Coffey, H. M., May, G., Flood, M. F., & Hansen, D. J. (2022). Helping families following sibling sexual abuse: Opportunities to enhance research and policy responses by addressing practical challenges. Aggression and Violent Behavior, 65, 101652. https://doi.org/10/gr2hnf
Rosenzweig, J. (2015). The parent’s guide to talking about sex: A complete guide to raising (sexually) safe, smart, and healthy children (Updated edition). Skyhorse.
Tener, D., & Silberstein, M. (2019). Therapeutic interventions with child survivors of sibling sexual abuse: The professionals’ perspective. Child Abuse & Neglect, 89, 192–202. https://doi.org/10/grw46x
Yates, P., & Allardyce, S. (2021). Sibling sexual abuse: A knowledge and practice overview. Centre of expertise on child sexual abuse (CSA Centre). https://www.csacentre.org.uk/app/uploads/2023/09/Sibling-sexual-abuse-report.pdf
Yates, P., & Allardyce, S. (2023). Sibling sexual behaviour: A guide to responding to inappropriate, problematic and abusive behaviour. Centre of expertise on child sexual abuse (CSA Centre). https://www.csacentre.org.uk/app/uploads/2023/09/Sibling-sexual-behaviour-English.pdf
