Child sexual abuse is a difficult thing to define. While an adult having contact with a child is easily defined as abuse, especially if that adult is related to the child, more difficult issues come into play when the perpetrator is another child in the family, especially when the child is 10 years old or younger. Cantwell (1988) reported several cases investigated in Denver in which children under the age of 10 years were molesting younger peers, sometimes siblings or cousins and sometimes unrelated children, in a variety of settings including multi-family households, school busses, and neighborhood children's homes. Parents may interpret this behavior at times as normal child sexual curiosity, or may spank the children to halt this behavior. Often in these cases, the child perpetrators were abused themselves at a young age, but, due to the shock experienced on discovery of the abuse and the focus on the "victim," they did not receive services and their own history of abuse was not discovered until later.


Typically sibling or cousin sexual contact is defined as "abuse" when it is marked by a five year difference; when the children are less than five years apart in age, the interaction is not deemed abusive unless force, coercion, injury, or penetration occurs. The criteria of force and/or coercion may be the most highly associated with negative outcomes, regardless of the specific sexual behavior (e.g., kissing, fondling, simulated intercourse, or exhibition) experienced (Haugaard and Tilly, 1988). Incidence of sibling or cousin sexual abuse varies greatly among studies, ranging from 10% to 40% among those reporting sexual abuse, although sibling and cousin sexual abuse are about equal in such samples (De Jong, 1988). Typically, the abuse begins when the victim is around six to seven years of age.

It is unclear whether "non abuse" contacts always result in psychological harm or maladjustment. It may be that normal sexual curiosity between siblings and cousins that happens only once is not harmful. As to repeated sexual contact between the children, two models have typically been proposed. In the first model of contact, often called "nurturance-oriented," the children consensually seek sexual contact with each other over time, in part to provide nurturing and affection that is missing elsewhere in the family. It may begin with elements of loyalty, mutual satisfaction, and support, and may or may not turn coercive or lead to abuse outside the home as the child grows older. Some argue, however, that sibling sexual contact during preteen and teen years, even if consensual, interferes with the development of social skills and support systems beyond the family. This may prevent appropriate separation and differentiation from the family (Cicirelli, 1995).

The second model of contact entails a clear attempt by the abuser to experience some power, either for its own sake or to possibly re-enact and master their own experiences of abuse. Research has attempted to study this type of abuse and isolate its effects. However, such abuse is often associated with sexual abuse and promiscuity, as well as additional family dysfunction, and it is difficult to determine the effects of sibling abuse as separated from other forms of abuse (Cicirelli, 1995).


Some of the research (Meiselman, 1978) comparing incest victims and non-abused women indicates that incest victims have more problems in romantic and family relationships, and more sexual problems. They appear to show no significant differences in regards to presence of depression, suicide risk, substance abuse, or anxiety, although they are likely to have more severe depression when it is present. Other studies (Herman, 1981) show that incest victims are more likely to suffer physical abuse in the family along with the sexual abuse, to experience teen pregnancy, to run away, and to make suicide attempts when compared to the average teen. Those attempting suicide are more likely to do so without obvious signs of depression, to attempt while using substances, and to attempt during the adolescent years between the ages of 14 and 16 (Goodwin, 1982). Finkelhor (1979, 1984) found college students reporting childhood sexual abuse had lower self-esteem, and others have found that incest victims were more likely to suffer more victimizing incidents over a longer period of time, and to wait longer for treatment after disclosure.

Edwall and Hoffman studied teens admitting and denying incest, as previous research (Russell, 1986) found that 23% of adolescent girls entering treatment reported some intrafamilial abuse. They found incest victims

  • were more likely to have experienced physical abuse, and their siblings were more likely to have experienced physical and sexual abuse
  • were more likely to abuse substances in general, but alcohol and stimulants were typically their drugs of choice, and they often started abusing alcohol by the age of 9 years
  • were more likely to have had a psychiatric hospitalization, to experience clinical levels of depression, and be at risk for suicide
  • were more likely to believe that their parents were ashamed of them and did not love them
  • were more likely to have required police involvement and to have been picked up by police for running away

They found a trend for an increased risk of abuse outside of the family, increased substance abuse by either or both parents, and increased history of divorce and remarriage in the family

Higgs and colleagues (Higgs et al, 1992) offered that children who experienced more frequent incidents of incest, who had a close relationship with the abuser, who experienced violence during some of the abuse and consent during other sexual experiences, and who engaged in more serious sexual behavior (i.e., intercourse) were more likely to become abusers themselves. Further, failing to internalize aspects of a nurturing and psychologically aware parent can lead to a failure to develop the kind of empathy that would inhibit abuse of others.


De Jong (1988) and Daie et al (1989) present several factors in families that can lead to sibling or cousin abuse. Abuse can arise in an environment that:

  • fails to protect the child, though poor supervision/monitoring and poor choices regarding babysitters and surrogate caretakers; examples include allowing children to remain in the care known siblings abusers, or a general lack of supervision of the children and knowledge about their activities in and out of the home
  • fails to set appropriate boundaries though inappropriate sleeping arrangements and clear parent-child hierarchies for child care; examples include allowing older opposite-sex children to sleep with parents in the absence of the same-sex parent, or flagrant nudity or lack of privacy in the family. Inappropriate parental interests in children's sexual development and experiences, or extremely relaxed views of sex, can both lead to greater freedom to explore sexual relations with peers and siblings. Others (Smith and Israel, 1987) argue that open parental sexual activity, especially in cases where one parent is having an affair, is an especially significant indicator; parents turn outside the family for their needs, marking a disintegration of family structure and an increase in anxiety in siblings. This may promote a sexual relationship between siblings in an attempt to nurture each other
  • lacks supervision and care by two parents; the absence of a parent can arise through physical absence from the home (e.g., divorce, death, abandonment, or work), or emotional absence due to physical or psychological illness (e.g., hospitalization due to depression, alcoholism, or dependent personality disorder). Some (Smith and Israel, 1987) have argued that this dynamic is one of the most salient of sibling incest families
  • is based on a multi-familial home were older children have caretaking responsibility for younger children; combined with poor boundaries, this situation can allow older children to pressure younger children into meeting their sexual interests and needs
  • allows physical abuse and neglect; Daie cites a case in which a physically abused boy in turn abused his sister, with sexual abuse being a minor part at first, but becoming the predominant form of the abuse over time
  • has a rigid family structure, discouraging open communication between children and parents, children and outsiders, and even between parents. They often show devaluing attitudes toward women, and enforce parental authority (often the father's power) unquestioningly over the family. This often leads to isolation, secretiveness, and enmeshment.

Others (Smith and Israel, 1987) argue that extreme repressive attitudes toward sex may lead to increased interest on the part of the children in exploring sex. A history of child sexual abuse in one parent may lead to the kind of denial and repression that prevents one parent from noticing the signs of sibling sexual activity. In either case, this rigid and repressing environment may be more likely to lead to parent-child abuse rather than sibling-sibling abuse. However, brother-sister abuse can result, modeling father-daughter abuse, as if the father's actions tacitly gave permission to the brother to abuse.

Cicirelli (1995) notes that the stereotypes of incest occurring primarily in poor, less educated, ethnic minority families has not been supported by literature. Sibling abuse happens in families at all levels of income and education, and across ethnicities.

Further, Smith and Israel (1987) note that there is no "type" of sibling who is likely to abuse, and personality characteristics are highly varied across abusers. Rather, sibling sexual abuse is the result of fragmenting and dysfunctional family processes, and not a cause of the family dysfunction. In response to the inadequacies of the family, a stronger and inappropriately close sibling bond may develop to compensate for the parents' dysfunction, or an abusive bond may develop and replicate the parents' dysfunction.

In families where abuse occurs, the dysfunction that led to the abuse may also lead to a poor response once the abuse is discovered. Wiehe (1990) noted that poorly responding families typically:

  • denied the allegations of abuse
  • ignored or minimized the abuse, explaining it as normal child behavior
  • acknowledged the abuse, but blamed or otherwise punished the abused child
  • acknowledged the abuse, but failed to protect the child and halt it
  • acknowledged the abuse, but their own dysfunction prevented them from responding to alter the environment

Poorly responding families may be perpetuating the abuse in two ways. First, they fail to halt the abuse in the home. Second, by failing in this, they create a sense that the child can not be protected, and that the perpetrator was "chosen" over the victim. Such actions and the feelings of helplessness and rejection that result may prompt the abused child to become an abuser as well, seeking power and revenge (Johnson, 1989).


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