There is no definite answer to this. It is based on numerous factors and individual differences. Sibling sexual abuse can happen in any family, even the most 'highly protective' and vigilant families. It does not discriminate. There is a common misconception that it only happens as a result of environmental factors and family difficulties such as domestic violence, abuse etc. HOWEVER it can also happen when there are no obvious troubles within the family but as a result of unknown internal conflicts/issues within the child who has caused the harm. It could be a result of prior abuse outside the family, learned behaviours, viewing of pornography, peer difficulties etc. The list goes on. It is imperative that the child who has harmed receives the appropriate help and support to work through what initially lead to the behaviours and to ensure they do not continue. It is imperative that professionals and parent's understand that the child who harmed are child first and foremost they should not be judged as adult sex offenders or 'mini paedophiles'. They are experiencing difficulties also and therefore require support, empathy and compassion to work through their difficulties, recognise the harm they have caused in a way that promotes responsibility, autonomy which encourages growth and rehabilitation. Although at times children recognise what they are doing is wrong in someway, many children lack the cognitive ability to understand the true extent of the damage, consequences and repercussions of their actions.
Below you will see a list of contributing factors but this is not exhaustive, nor limited. Again, each child and individual circumstances differ. When a child engages in harmful sexualised behaviours . Access to Pornography
Today the ease of access to Porn is an increasing factor as to why children may sexually harm others. Children that view porn may experience distortions of what healthy and age appropriate sexual activity is. They may try to imitate adult sexual activity that they have viewed without recognizing the damage it can cause or take into consideration age, consent etc. Own experience of sexual abuse
Some children may have experienced sexual abuse or trauma themselves and may repeat the same behaviours with their siblings. Some children may not recognise it as abuse at the time. This is not to say that everyone who experiences abuse will go onto abuse others as this is certainly not the case. Neglect
Children who experience physical or emotional neglect, and are frequently left without adult supervision, may be more likely to engage in sexual activities. They may try sexual activities they have learned from other children or from pornography. They may experiment on their own, to learn how to get sexual pleasure. Sexual activity between siblings which begins in this way might, at first, appear experimental and mutual. However, because of the power differences between children, it rarely is. If the behaviour continues or escalates, it can become abusive, especially if one of the children wants to stop and the other doesn’t.
Lack of Sexual Education
At present sexual abuse by a sibling is not discussed in sexual education classes. We hear od 'stranger danger' adult on child abuse, even peer or peer but nothing is mentioned about other children within the home. This is why it is so important to normalise the conversation. In doing so children will understand the impacts, boundaries and feel comfortable reaching out if it is happening. They will know where to turn to for support.
Children and teens who are not taught in an age-appropriate way about their physical and sexual development are more likely to engage in sexually intrusive behaviour. They may lack the accurate knowledge to make appropriate decisions or manage overwhelming feelings in relation to sexual desires. They may view there sibling as a safe person to explore such behaviours with. Inadequate Socialisation/Peer Pressure
Children who lack social interactions with their peers may be more likely to sexually abuse younger siblings. They may feel less experienced or advanced sexually as their peers. They may feel under pressure to match their peers sexual development. There is huge pressures on children to be sexually active. There can be an immense peer pressure to be engaging in such activities especially if their friend circle already have girlfriends/boyfriends. Many children can be taunted for being frigid, gay etc if they are not as sexually active as their peers. This can cause emotional turmoil, stress and pressure. Some children have reported this a being a contributing factor.
Children's brains have not yet developed the full capacity to control their impulses or be fully aware of the consequences of their actions. Their sexual curiosity and desires may be greater than their self-control therefore they may act on these impulses with a sibling. Simply because of living in the same household and frequent access/opportunity. It can be easier to get a younger sibling to engage in the behaviours rather than a peer of similar age.
Admitting that Sibling Sexual Abuse could be happening in your home is extremely difficult. The most important thing is to get help and support for everyone