Sexual interactions among siblings and cousins: experimentation or exploitation?

Incest by cousins has not been well documented compared with sibling incest. The purpose of this study was to describe the features of incest by cousins and siblings presenting to a sexual assault center and to differentiate cases of abusive behavior from normal sexual exploration. Four criteria were considered indicative of abusive behavior: (1) age difference of greater than or equal to 5 years between victim and perpetrator; (2) use of force, threat, or authority by abuser; (3) attempted penile penetration; and (4) documented injury in victim. Of 831 sexually abused children less than 14 years of age evaluated for sexual assault complaints, 49 cases of cousin incest (5.9%) and 35 cases of sibling incest (4.2%) were identified. A total of 54 male cousins abused 8 boys and 41 girls; brothers abused 3 boys and 32 girls. The victims' median age was 5 years for cousins and 7 years for siblings. The perpetrators' mean age was 16.2 years for cousins and 15.5 years for siblings, with only 16 (19%) of all perpetrators being greater than 16 years old. Of the perpetrators, 66 (79%) were greater than or equal to 5 years older than their victims. All 18 victims with age differences of less than 5 years met one or more of the other abusive criteria. A similar pattern of adolescent perpetrators having abusive sexual contact with young children was demonstrated by analysis of cousin incest and sibling incest in this study. Appropriate case management requires understanding of normal sexual experimentation and recognition of the abusive nature of these cases.