Another researcher stated that about 30% of all perpetrators of sexual abuse are related to their victim, 60% of the perpetrators are family acquaintances, like a neighbor, babysitter or friend and 10% of the perpetrators in child sexual abuse cases are strangers. Child sexual abuse offenses where the perpetrator is related to the child, either by blood or marriage, is a form of incest described as intrafamilial child sexual abuse.

The most-often reported form of incest is father-daughter and stepfather-daughter incest, with most of the remaining reports consisting of mother/stepmother-daughter/son incest. Father-son incest is reported less often, however it is not known if the prevalence is less, because it is under-reported by a greater margin. Similarly, some argue that sibling incest may be as common, or more common, than other types of incest:

Prevalence of parental child sexual abuse is difficult to assess due to secrecy and privacy; some estimates show 20 million Americans have been victimized by parental incest as children.