If incest is as prevalent as this California social worker contends, one in twenty Americans is a participant; victimized girls outnumber boys seven to one, and father-daughter relationships predominate, often with mother as ""silent partner."" A grim subject, even without the loosely cited statistics, but narrator Forward, a victim and serf-styled ""expert"" therapist, brings case histories, a psychology background, and a smattering of anthropology to her examination of this increasingly publicized phenomenon. Her conclusions are drawn not from a controlled study nor from a lifetime's experience but from personal observations after several years of clinical work. They seem most appropriate for a professional audience, rather than victims or the casual reader, but lack unconditional authority because of the informal mode of investigation and the pedestrian quality of presentation. She looks specifically at basic dynamics, at particular combinations (father-daughter, mother-son, siblings, father-son, mother-daughter, grandfather-granddaughter), and at the kinds of treatment she has found most effective. While aggressors often belittle the importance of the incidents, victims rarely do; these cases repeatedly show patterns of conflicting feelings, low self-esteem, and guilt lugged around for years, generally relieved by confession and responsive to psychotherapy--group treatment and psychodrama especially seem to clear the air. A serious approach, which neither trivializes nor overdramatizes, yet never really establishes its soundness.