Of the perpetrators, 66 (79%) were greater than or equal to 5 years older than their victims. 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. The victims' median age was 5 years for cousins and 7 years for siblings. A total of 54 male cousins abused 8 boys and 41 girls brothers abused 3 boys and 32 girls. 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. 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. 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. Incest by cousins has not been well documented compared with sibling incest.
