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What is Sibling Sexual Trauma?

Sibling sexual trauma is sexual behavior that:

  1. Happens between children in the same biological family and/or living in the same house 

  2. Goes beyond age-appropriate mutual curiosity

  3. Causes emotional and/or physical harm 

As the 2022 UK Sibling Sexual Abuse Project notes, there is no universally accepted definition of sibling sexual abuse (a more commonly-used term).  The definition used for their project was harmful sexual behaviour, with a victimising intent or outcome, between children who self-identify as siblings.

Most often, an older brother violates his younger sister. But it can happen between children of any gender and age. It can happen among biological siblings, step families, adoptive or foster families, cousins being raised together.  


Usually there is some kind of abuse of power or position in the family, threat, or intimidation. But these can be subtle and hard to spot. The limits of normal curiosity can be fuzzy. The harm may not be obvious to parents or outsiders. It can be hard even for the children themselves to understand who is truly responsible and who was violated. It is frighteningly easy for adults to underreact or overreact. And the risks of reacting inappropriately are great.  


Sibling sexual trauma defies common language, categories, and understanding around sexual abuse and assault. Sibling Sexual Abuse* (SSA) is a more commonly used term. Sibling Incest is another term that has been used. This site uses the term Sibling Sexual Trauma in keeping with Cora Haskins’ approach in her 2003 publication

...sexual contact between two siblings that is experienced by the survivor as traumatic.” 


This term keeps the focus on the harm that was done, determined by the person most affected by it. It does not depend on the intent or level of responsibility of the sibling who caused the harm, and it does not depend on a legal definition of abuse.

No one truly knows how many people are adversely affected by sibling sexual trauma. We know that most children do not talk about it when it happens. Some may find a way to tell someone later in life, but there’s no way to know how many do not. And even fewer people’s stories are officially reported in a way that shows up in medical or crime data. In a Jan 2021 review, the Centre of Expertise on Child Sexual Abuse (CSA Centre) of the UK concludes that siblings are the family member most likely to cause sexual harm to a child. The review cites surveys finding that approximately 15% of adults recalled some kind of sexual activity with a sibling during their own childhood, and 5-10% reported that the activity was harmful or coercive. The 2022 RCEW National Project on Sibling Sexual Abuse calls for increased awareness of the reality that siblings are the most common cause of sexual harm to children.  

Siblings Too Podcast: Breaking the Silence that is Keeping Sibling Sexual Abuse Quiet with Fleur Strong. Project Manager, RCEW National Project on Sibling Sexual Abuse

  • Sexual trauma caused by cousins or other children is also unfortunately very common. 

  • Sometimes sexually abusive behavior toward a sibling continues into adulthood or begins in adulthood.

  • Although this site does not specifically address these circumstances, the information provided may be helpful to those who are facing them. 

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