This survey included health visitors, nurses for mentally abnormal offenders and in regional secure units for rehabilitation of offenders, and medical students. The English legal definition of incest was used: consent to intercourse of a woman over 16 with grandfather, son, brother, half-brother, or father; and a man with woman known to be his granddaughter, daughter, sister, half-sister, or mother. Analysis of variance was used to examine whether the relationship between adult and child or the type of sexual activity involved influenced responses. Results revealed that the type of sexual activity influenced the responses much more than the relationship between adult and child. All respondents believed that the least harmful of parent-child relationships was more harmful than the most harmful relationships between siblings. Female respondents were sympathetic to victims of either sex. 3 figures, 2 tables, 12 references. (Author abstract modified)