BASED ON A SAMPLE OF 58 MALE AND 28 FEMALE FELONS AND THEIR FIRST-DEGREE RELATIVES, INTERVIEW AND RECORD DATA WERE GATHERED AND COMPARED TO TEST THE FOLLOWING HYPOTHESES: (1) THE PATHOGENETIC FACTORS RELEVANT TO SOCIOPATHY ARE MULTIPLE AND ADDITIVE; (2) SOCIOPATHIC MEN AND WOMEN OCCUR IN THE SAME FAMILIES; (3) THE LOWER PREVALENCE IN WOMEN IS DUE TO THE THRESHOLD FOR WOMEN BEING MORE VARIABLE THAN THE THRESHOLD FOR MEN; AND (4) THE SAME PROPORTION OF FAMILIAL AND NONFAMILIAL FACTORS IS IMPORTANT IN THE AETIOLOGY OF BOTH MEN AND WOMEN. RESULTS OF THE MULTIFACTORIAL ANALYSIS INDICATE THAT SOCIOPATHY IS HIGHLY FAMILIAL FOR BOTH BLACK AND WHITE FAMILIES AND THAT SOCIOPATHY IN MEN AND WOMEN CLUSTERS IN THE SAME FAMILY ALTHOUGH IT IS MUCH MORE FREQUENT IN MEN. THE PREVALENCE OF THE SEX DIFFERENCE APPEARS TO BE DUE TO SEX-RELATED CULTURAL AND BIOLOGICAL FACTORS CAUSING THE THRESHOLD TO BE MORE FLEXIBLE IN WOMEN. THERE IS NO EVIDENCE OF A GENETIC DIFFERENCE IN ITS PREVALENCE AND TRANSMISSION ACCORDING TO RACE. THE MULTIFACTORIAL MODEL PROVIDES AN EXPLANATION FOR THE STRIKING SEX DIFFERENCES IN SOCIOPATHY TRANSMISSION. THE HIGH CORRELATION AMONG SIBLINGS INDICATES THAT ENVIRONMENTAL FACTORS COMMON TO SIBLINGS CONTRIBUTE TO THE AETIOLOGY OF SOCIOPATHY, AND THE GREATER DEVIANCE IN PARENTAL HOME EXPERIENCES OF SOCIOPATHIC WOMEN IS EVIDENCE OF THE IMPORTANCE OF FAMILIAL ENVIRONMENT. TABULAR DATA AND REFERENCES ARE PROVIDED. (AUTHOR ABSTRACT MODIFIED--DAG)