Background Incest is defined as any sexual activity between close blood relatives including step relatives and family members who are forbidden by law to marry. It is a problem that can be seen in all the social classes in developed and undeveloped societies.

A case of father-son incest is presented. There were three sexual involvements over a period of 6 weeks that ranged in activity from genital fondling to anal penetration. The father was the initiator of the activity and was drunk during each of the episodes.

Six families are described in which 10 sons were involved incestuously with a natural father (N=4) or step-father (N=2). Father-son incest as a part of the spectrum of child abuse appears to be a more frequent clinical entity than was thought previously.