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What is sibling sexual abuse?

Updated: Aug 8, 2023

It is perfectly normal for even very young children to demonstrate sexual curiosity, which is why it can be difficult to define when child sexual behaviour – especially towards other children – is abusive. Pair that with the inherent discomfort around intrafamilial sexual relationships and it becomes even more difficult to address.

Although there are many aspects of sibling sexual abuse that we do not know about, estimates show that this form of intrafamilial abuse is up to three times more common than a child being abused by a parent. Because the line between sexual curiosity and abuse is sometimes unclear between children, we have lacked a coherent care infrastructure to address the abuse and safeguard children within the family home. As such, professionals in health and social care are now paying closer attention to how we can define sibling sexual abuse, support children in harmful situations, and help adult survivors heal.


Sibling sexual abuse is a kind of intrafamilial abuse that happens between children (under the age of 18). The term ‘sibling’ can encompass a broad range of biological and non-biological relationships, including biological siblings, step-siblings, half-siblings, foster siblings, and social siblings who are brought up within the same familial setting. Sibling sexual abuse can be initiated by children of any age.

Cases in which one sibling is an adult and the other a child are distinct because the abuse is more easily defined. However, this does not mean sibling sexual abuse is less severe; it has the potential be just as harmful as abuse committed by parents or adult family members.

It can involve a wide range of behaviours, including sexual touch, penetrative sex acts, and non-contact forms of abuse (e.g. voyeurism, looking at or sending sexual images). Because siblings typically share a household, and because sibling interactions often happen away from the gaze of adults, abuse can happen regularly and over a long period of time.

Why has it been so hard to define?

As above, sibling sexual abuse can involve a wide range of behaviours and often over a long period of time, and as such its impacts might not be felt until adulthood. In fact, in the majority of cases the abuse is not disclosed until adulthood, and for a range of reasons children may not be believed when they speak up about intrafamilial abuse. This is in part due to stereotyping, i.e., the image adults have in their heads about what an abuser looks like (typically a ‘creepy old man’). It is often very difficult to confront the truth that children and other loving and caring family members can cause sexual harm. Other reasons for disbelieving include anger and shame even thinking about child sexual abuse and therefore dismissing it, or fear of the consequences of speaking out and potentially causing a family crisis.

In cases of sibling sexual abuse more specifically, siblings can have complex power dynamics influenced by their age, birth order, and gender. Older siblings (and/or first-borns) generally have a broader range of tactics to use to exert power, as they are assigned authority over younger siblings by parents, and are more likely to be believed by parents. Physical and psychological threats are also more credible when made by older siblings.

Gender is salient as the most reported abuse between siblings involves an older brother abusing a younger sister. Persistent cultural and historical shaming around girls’ bodies leaves them especially vulnerable and unlikely to speak up. However, gender is far from the only factor: a significant minority involves a number of children being harmed within a family, or cases in which a sibling both harms and is harmed through sibling sexual abuse. Furthermore, 1 in 6 men report experiencing unwanted and abusive sexual experiences in childhood. While this figure stands at 1 in 3 for women, there are still no clear-cut gendered lines to draw. Gendered assumptions about who can be abused and who can be an abuser can render certain abuses invisible and disbelieved.

Sometimes, difference in age can more clearly indicate who is exerting abusive power over who. But often with sibling abuse, and especially in cases where there is mutual abuse, there is not always a clear ‘victim’ and ‘perpetrator’. Furthermore, if a child is committing abusive acts towards a sibling, it raises questions about sexual abuse happening elsewhere in the family or in the child’s life because often, the child causing harm is being harmed themselves. This revelation in itself can cause distress and an upheaval of trust within the wider family, and is difficult to confront fully without specialist support.

Reciprocity and consent can often be unclear in sibling relationships. Some sibling relationships become eroticised as a way of coping with other stresses and traumas in their lives, but over time, one sibling may withdraw consent, causing the other to use coercion to cause the activity to continue. The boundaries between problematic behaviour and abusive behaviour therefore may shift over time. There is also the misconception that abusive acts committed by children are less harmful, and because children generally have less access to consent and relationship education, they may not realise what is happening to them is abusive.

Finally, sibling dynamics are often very complex. There is a tendency to reduce sibling relationships as either warm and nurturing or rivalrous and competitive. It is rarely that binary, however, and even healthy and caring sibling relationships can involve a degree of arguing, play fighting, and teasing. Sibling relationships are often unrestrained and honest, and are therefore important for childhood development in skills such as reasoning, empathy, perspective-taking, and conflict resolution, as well as helping children develop a sense of self and self-esteem. However, in some cases, sibling hostility – due to rage, jealousy, or other traumas - can escalate to bullying, psychological mistreatment, physical abuse, and sexual abuse. While it is sometimes difficult or uncomfortable for a caregiver to understand childhood sexuality, a clear line must be drawn between healthy curiosity and behaviours which are inappropriate, violent, or coercive.

Normal sexual exploration/curiosity vs abuse

Child sexual curiosity is a normal part of their development, which is also why it has been sometimes difficult to assess what are normative developmental behaviours between children and what sexual activities are harmful and exploitative.

Certain sexual behaviours in children and adolescents are healthy, though what constitutes ‘healthy’ is different for children than for adolescents, or may depend on the developmental stage of the individual child. For children, normative developmental behaviours include what clinical psychologist Toni Johnson calls ‘information-gathering processes’, such as games where children look at and touch their own or each other’s bodies, as in the case of playing doctor or playing house. Healthy sexual curiosity from children is paired with a more general curiosity about the world and social interactions: ‘The child’s interest in sex and sexuality is balanced by curiosity about other aspects of [their] life’, Johnson explains, and their sexual explorations are ‘generally light-hearted and spontaneous.’ Further, when inappropriate behaviours, such as touching, stop upon adult intervention, this is a sign of curiosity rather than abuse. If it continues in secrecy, this suggests a sustained pattern of abusive behaviour.

For adolescents, behaviours that include kissing, flirting, and foreplay that are more oriented around intimacy, arousal, and orgasm are the norm. Children exhibiting adolescent curiosity, or sexual behaviours expected of children that carry through to adolescence, are cause for concern.

Abusive activities can range from behaviour that is inappropriate to severe sexual assault. The following criteria are used to assess whether a child’s sexual behaviour is harmful:

  • It happens more regularly than expected for healthy development

  • It interferes with the child’s development

  • It occurs with coercion, intimidation, or force

  • It causes emotional distress

  • It occurs between children with a significant age gap or a difference in cognitive or developmental ability

  • It repeatedly recurs in secrecy after caregiver intervention

The Brook Traffic Light tool is sometimes used to recognise concerns about a child’s safety in cases of sibling sexual activity. If an activity is outside the developmental norm, or does not stop after a parent/adult tells the child not to, it is far more likely to be harmful to the children involved.

Pathways to intervention and prevention

The silence around sibling sexual abuse has made it difficult to define and address, and disbelief greatly exacerbates the impact of the abuse. Not only it is able to continue, but the child harmed can feel invisible and/or blame themselves for what is happening. Anger towards parents for failing to listen and prevent the abuse may continue for decades afterwards. However, it is important to recognise that parents’ failure to report does not mean they will not accept specialised support; often failure to intervene is a consequence of parents’ own shame and sense of ‘failing as a parent’ to prevent the abuse in the first place.

The way adults and professionals treat the sibling who harms needs to be carefully considered, as it is often the case that the child has been sexually harmed themselves. They require specialist support and should not be seen as ‘mini-sex offenders’, because research has shown their pathways into and out of the abuse are significantly different than in the case of adult perpetrators of child abuse. The issue must be seen as one that involves the entire family, not just a ‘problem child’, and measures including living and contact arrangements must be made to ensure safety for all children involved.

Ultimately, this common form of intrafamilial abuse is generally a sign of other abuses, traumas, or familial conflict within the children’s lives. Careful and specialised support is needed to help parents deal with this emotionally difficult problem and to safeguard all children involved.


If you or someone you know has experienced sibling sexual abuse, you are not alone. Below is a list of resources with further links to information and support.

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