Feb 2023

Key messages from research on children and young people who display harmful sexual behaviour

DMSS Research

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Key messages

The term ‘harmful sexual behaviour’ describes a continuum of behaviours displayed by children and young people under 18, ranging from those considered ‘inappropriate’ at a particular age or developmental stage to ‘problematic’, ‘abusive’ and ‘violent’ behaviours.

There are no accurate prevalence figures on the full spectrum of harmful sexual behaviours. However, available data suggests that under-18s are responsible for a significant proportion of child sexual abuse, and there is considerable concern about widespread and ‘normalised’ sexual harassment and abuse between students in schools.

In pre-adolescent children, behaviour is more likely to be at the ‘inappropriate’ or ‘problematic’ end of the continuum. Most pre-adolescent children displaying harmful sexual behaviour have themselves been sexually abused or experienced other kinds of trauma or neglect.

Older children and young people displaying harmful sexual behaviour are mostly boys, many of whom have a history of adverse childhood experiences and family difficulties.

It is important to remember that most sexually abused children and young people do not go on to abuse others, and the majority of children and young people displaying harmful sexual behaviour do not commit sexual offences as adults.

The limited research into technology-assisted harmful sexual behaviour suggests that boys who engage ‘only’ in watching images of child sexual abuse online have far less troubled histories than those who commit other sexual offences. There may sometimes be a link between viewing online pornography and subsequent harmful sexual behaviours.

There is limited published research on effective interventions, particularly at the ‘problematic’ end of the continuum, although there is a general consensus that interventions need to be holistic, child-focused and involve parents/carers.

Professionals working with children need knowledge and skills to respond to harmful sexual behaviour, and to create organisational contexts which maximise safety from abuse. Prevention education should take a long-term, ‘whole school’ approach to healthy relationships, and involve children and young people in development and delivery. Broader public health approaches which challenge gender inequality and patriarchal values and attitudes are also required.

What is harmful sexual behaviour?

Harmful sexual behaviour has been defined as sexual behaviour by under-18s that is “developmentally inappropriate, may be harmful towards self or others and/or be abusive towards another child, young person or adult”. Those either exhibiting or being harmed by such behaviours may be male or female. Behaviour that is ‘developmentally appropriate’ in young children may be concerning in adolescence, while other behaviours, normal in adolescence, would be worrying in younger children.

Sexual behaviours in children and young people have been described as existing on a continuum ranging from what is widely considered ‘normal’ and developmentally expected, through ‘inappropriate’ and ‘problematic’, to ‘abusive’ and ‘violent’. The concept of ‘normal’ sexual behaviour by children and young people is not straightforward: what is ‘expected’ or ‘common’ at different developmental stages is culturally and historically variable, and behaviour considered ‘normal’ by some people in some contexts may also be problematic or abusive. For example, behaviour experienced as harassment by many victims is widely regarded as normal by many other young people.

The extent of harmful sexual behaviour

Among referrals to local authority children’s services in England during 2021/22 where sexual abuse was assessed to be a concern, 40% involved harmful sexual behaviour. However, accurate figures for the extent of harmful sexual behaviour do not exist, not least because it covers such a broad spectrum of behaviours, most of which do not come to agencies’ attention.

The vast majority of harmful sexual behaviour involves children and young people who are well known to each other. It has been estimated that between a quarter and a half of harmful sexual behaviour involves siblings or close relatives such as cousins, nephews and nieces.

A number of large-scale surveys indicate that girls are routinely subject to harmful sexual behaviour in their everyday lives. A survey on sexism in secondary schools found a highly gendered picture of sexual harassment: 37% of girls reported experiencing sexual harassment, compared to 6% of boys. A rapid review of sexual harassment and assault in schools and colleges in England found that sexual harassment was ‘commonplace’, and nearly 90% of girls – as well as 50% of boys – said being sent explicit pictures or videos of things they did not want to see happened ‘a lot’ or ‘sometimes’. In a similar review in Wales, girls described a constant pressure from boys to send nude photographs, and more than half of boys said they were personally involved in sexual harassment.

What is known about children and young people who display harmful sexual behaviour?

Pre-adolescent children

While the behaviour of some pre-adolescent children may be ‘problematic’, it is seldom intentionally abusive. Many pre-adolescent children displaying harmful sexual behaviour have been sexually abused or exposed to developmentally inappropriate sexual experiences, such as seeing pornography. Their behaviour may be a way of communicating what has happened to them or an indirect response to other factors in their lives, including other forms of trauma and neglect.


The early teens are the peak time for the occurrence of harmful sexual behaviour. The vast majority of adolescents who display such behaviour are male, but it is rare for research or practice to focus on the significance of gender.

Most research has been conducted with criminal justice or ‘clinical’ populations and has repeatedly found that boys who have committed a sexual offence, or have been referred to specialist services because of concerns about their behaviour, generally have other major difficulties in their lives; these include experience of physical or sexual abuse or neglect, witnessing domestic violence, or having parents with mental health or substance abuse issues. Adverse childhood experiences tend to be more strongly linked to antisocial behaviour in males than in females.

Adolescents displaying abusive or violent sexual behaviour are, like their peers whose offending behaviour is non-sexual, likely to have low self-esteem, poor social skills and difficulties with anger, depression and peer relationships.

Given these factors, it is unsurprising that adult outcomes are often poor. While numerous studies suggest that rates of further sexual offending are low, a recent 10- to 20-year follow-up of young people previously referred to a specialist service found that only a quarter had entirely successful life outcomes; unstable relationships and living situations, health issues, and drug and alcohol misuse were common experiences.

When harmful sexual behaviour involves siblings, it may occur within a context of family violence and neglect. Compared with other intra-familial abuse, it may occur more often and over longer periods, and be more likely to involve intrusive and penetrative acts.

It is increasingly recognised that some forms of sexual harassment and abusive behaviours between adolescents are so commonplace in schools and colleges that some young people may regard them as ‘normal’. More highly abusive and violent sexual behaviour may occur in the context of delinquent groups or gangs, where sexual violence can be coerced as well as normalised. Higher levels of general antisocial behaviour tend to be shown by adolescents who behave in sexually harmful ways towards their peers, compared with those whose harmful sexual behaviour targets younger children.

It is important to remember that most victims of sexual abuse do not go on to abuse others, and that most children and young people who display harmful sexual behaviour do not go on to sexually offend as adults. However, older adolescents who abuse younger children, and those whose sexual behaviours involve violence, are at greater risk of further sexual offending.

Children with learning disabilities or autism

Children and young people with learning disabilities are more vulnerable both to being sexual abused and to displaying inappropriate or problematic sexual behaviour; in one large UK study, 38% of under-18s referred to specialist services because of harmful sexual behaviour were assessed as having a learning disability. However, it is likely that the high level of adult supervision of children and young people with learning disabilities means that their sexual behaviour is more likely to be observed and problematised.

Reasons why some children and young people with learning disabilities may be more likely to display harmful sexual behaviour include having less understanding that some sexual behaviours are not acceptable, and fewer opportunities to establish acceptable sexual relationships; receiving less sex education; struggling with social skills; and relating more easily to children younger than themselves.

While research suggests that individuals with autism spectrum disorders are not at increased risk of offending generally, a proportion of harmful sexual behaviours in individuals with autism may result from specific difficulties in understanding what other people may be thinking or feeling.

The Good Way’, a strengths-based model for working with adolescents with learning disabilities, has been developed in New Zealand. The ‘Keep Safe’ manualised group cognitive behavioural therapy intervention in the UK is another recent development.

Girls and young women

Most research into harmful sexual behaviour is based on male populations or includes only small numbers of girls. However, studies have found that girls and young women displaying abusive sexual behaviour are likely to have experienced more victimisation (including intra-familial sexual abuse, other forms of abuse and frequent exposure to family violence) than boys. Two UK studies found that, compared to boys, girls who sexually harmed had typically experienced more chronic and extensive maltreatment in childhood, had been sexually abused at an earlier age and were more likely to have been abused by more than one person.

Harmful sexual behaviour tends to be identified at a younger age in girls than in boys, and tends to involve younger victims. It is relatively rare for girls’ abusive sexual behaviour to involve the use of physical force. Girls displaying harmful sexual behaviour are less likely than boys to be charged with an offence, in part because they and their victims tend to be younger – but, like boys who display harmful sexual behaviour, they often have difficulties in school and relatively high levels of learning difficulties.

Barnardo’s has developed Girls’ Talk, a resource pack for practitioners supporting girls who have displayed harmful sexual behaviour to develop healthy sexual relationships.

Technology-assisted harmful sexual behaviour

Although the use of technology is now fundamental to many people’s everyday interactions, research into the role of technology in harmful sexual behaviour is still very limited. Given the changing context in which children and young people use social media – with Wi-Fi and mobile data now enabling internet access away from home and adult supervision – it is a challenge to determine what are developmentally ‘normal’ as opposed to ‘problematic’ online behaviours. For example, a UK survey found that 48% of 11–16-year-olds had viewed pornography – and among those who had done so, 34% reported seeing it once a week or more.

One UK study found that, among young males displaying both online-facilitated and ‘offline’ harmful sexual behaviour, the developmentally inappropriate use of pornography had been a trigger for their offline behaviour in more than half of cases. In a study of young people across Europe, boys who regularly watched online pornography were found to be significantly more likely to hold negative gender attitudes; furthermore, regularly watching pornography and sending/receiving sexual images or messages were both associated with increased probability of being sexual coercive.

The relationship between viewing pornography and subsequent harmful behaviours is likely to depend on the type and content of material viewed, the motivation for viewing, and factors such as age at first viewing and the intensity of viewing. It may be that children and young people at greater risk of engaging in such behaviour are more likely to seek out pornography, or that the relationship is multi-directional.

Some studies indicate that, compared with those who commit other kinds of sexual offence, young people who are identified ‘only’ as viewing pictures of child sexual abuse are generally less likely to have experienced adverse childhood experiences, and more likely to come from stable and economically advantaged family backgrounds and be achieving well educationally.

Effective assessment

There is little published research on appropriate ways of assessing children and young people who display harmful sexual behaviour. However, there is general agreement that any assessment should take their social, emotional and cognitive development into account, along with their and their family’s whole circumstances – including any prior experience of abuse. Viewing harmful sexual behaviour through the lens of trauma is important, to identify vulnerabilities and areas of unmet need./p>

There is therefore general support for the use of holistic assessment tools. These tools consider the specific risks of the child or young person’s behaviour (including online) and motivations, and their needs and strengths at individual, family and community levels. A number aim to assess the likelihood of harmful sexual behaviour persisting or escalating, but none has been validated as a predictive measure.

Assessments can take place for a variety of purposes: clinical, child protection or criminal justice. It is important to remember that children and young people displaying harmful sexual behaviour are a diverse population, and the crossover of ‘victim’ to ‘perpetrator’ may not always be clear. A tiered approach, ensuring that the level and intrusiveness of assessment matches the seriousness of the behaviour and the legal context, has been proposed.

Effective interventions

It is important to recognise that most evidence to date on the effectiveness of interventions comes from studies of boys and young men who have been convicted of sexual offences. There is little evidence on interventions at the ‘inappropriate’ or ‘problematic’ end of the continuum, or on interventions involving girls or children with learning disabilities.

Intervention approaches to display harmful sexual behaviour tend to be ‘gender-blind’ and rarely address male privilege, gender inequality, ‘toxic’ forms of masculinity or victim-blaming myths that underpin sexual harm. It has been suggested that a more sociological and feminist-informed approach to intervention may be required, and that failing to address the role of patriarchal values and attitudes in the development of harmful sexual behaviours may leave children and young people at risk of involvement in further gendered violence in adolescence and adulthood.

Most evaluated interventions incorporate a cognitive behavioural therapy (CBT) element. However, a recent Cochrane review identified only four randomised-control trials of CBT eligible for inclusion; it concluded that, on the basis of the available evidence, it is uncertain whether CBT reduces harmful sexual behaviour compared to other treatments.

However, there is broad consensus that interventions need to be proportionate to the nature and extent of the behaviour, and to the child or young person’s age and developmental stage; joined-up processes are needed, to avoid agencies under- or overreacting to harmful sexual behaviour.

Involving parents and carers in treatment appears to be crucial. The most valuable approaches are structured and holistic, considering the child or young person’s whole situation (not just their problem behaviour), equipping them with interpersonal skills as well as knowledge, and underpinned by a therapeutic relationship built on trust.

Given that many children and young people displaying harmful sexual behaviour have themselves experienced abuse, trauma-informed interventions identified as effective with child victims are also relevant.

Historically, many interventions were derived from models developed with adult sex offenders and are now widely considered to be inappropriate. There has been a gradual shift towards more ecological, developmentally sensitive and individualised approaches to both assessment and intervention. This has occurred alongside an increased interest in resilience models, which aim to mobilise the child or young person’s strengths and reduce the risk of repeat harmful sexual behaviour by helping them develop positive relationships and pro-social ambitions. Although there has been little evaluation of such approaches, their principles are consistent with what we know from offender follow-up studies about factors contributing to better outcomes – such as having aspirations and hopes for the future, stable and enduring adult relationships, better educational achievement, and opportunities and skills to gain employment.


There continues to be a ‘sexual double standard’ through which boys’ sexual behaviours – including sexting – increase their status with male peers, while girls are condemned or ‘slut-shamed’ if images of them are shared. Research suggests that many young people learn about sex primarily through pornography, leading young men to think that sex should be ‘aggressive’ and ‘forceful’.

After the Everyone’s Invited website highlighted experiences of sexual abuse and harassment in schools across the UK, Ofsted and Estyn found that some teachers and school leaders underestimated the scale of the problem, confirming an earlier survey in which 61% of girls aged 11–16 said school staff sometimes or always dismissed sexual harassment as just banter or ‘boys messing around’. A quarter (27%) of secondary teachers would not feel confident tackling a sexist incident if they experienced or witnessed it in school.

Punitive and sanctions-based approaches to harmful sexual behaviour have been found to reduce disclosure by children – who do not see them as effective – and limit staff decision making.

Most prevention-focused activity takes the form of school-based programmes to raise awareness of sexual exploitation, internet safety, consent and sexual harassment, and to promote healthy relationships. The rationale is generally that unhealthy attitudes and behaviours need to be addressed early, at an individual level and at community and societal levels.

Evaluations of such school-based programmes have found only minimal impact on behaviour, although they can build confidence, increase knowledge and change some attitudes that may legitimise harmful behaviours. The most effective approaches are longer-term and involve children and young people in development and delivery. They also take a whole-school approach: alongside classroom-based sessions, schools need to consider how they promote healthy relationships across the curriculum, in their bullying and safeguarding policies, in their pastoral support and in the information and support they give parents.

New government guidance for schools and colleges in England on dealing with sexual violence and harassment emphasises the importance of a whole-school approach to safeguarding, a strong preventative education programme, and a zero-tolerance approach to inappropriate behaviour in order to prevent problematic, abusive and/or violent behaviour in the future.

A much broader approach to prevention has recently been advocated, incorporating a public health approach to addressing underlying risk factors; a gendered analysis of inequalities, attitudes and norms as drivers of abuse; and psycho-social education and interventions at an individual level.

Read the earlier 2018 paper