STUDIES ON INBRED STRAINS OF LABORATORY MICE AND DOGS INDICATE THE POTENT EFFECT OF GENETIC FACTORS IN DETERMINING AGGRESSIVE BEHAVIOR, BUT THEY ALSO SUGGEST THE COMPLEX INTERACTIONS BETWEEN GENOTYPES AND THE ENVIRONMENT. OTHER STUDIES INVOLVING HUMANS, ALSO SHOW SOME GENETIC INFLUENCE IN ANTISOCIAL BEHAVIOR IN PEOPLE. TWIN COEFFICIENTS IN ONE STUDY WERE FOUND TO BE HIGHER FOR MONOZYGOTIC THAN FOR DIZYGOTIC PAIRS WITHIN ALL TYPES OF OFFENSES, BUT PARTICULARLY FOR CRIMES OF VIOLENCE. RATES OF REGISTERED CRIMINALITY AMONG ADOPTEES WITH CRIMINAL ADOPTIVE AND BIOLOGIC RELATIVES WERE FOUND TO BE HIGHER THAN RATES AMONG ADOPTEES WITH CRIMINAL ADOPTIVE AND NONCRIMINAL BIOLOGIC FATHERS; THE RATE OF CRIMINALITY WAS HIGHER FOR ADOPTEES WITH CRIMINAL ADOPTIVE FATHERS AND NONCRIMINAL BIOLOGIC FATHERS THAN FOR THOSE WITH NONCRIMINAL BIOLOGIC AND ADOPTIVE FATHERS. THIS SUGGESTS AN INTERACTIVE EFFECT BETWEEN GENES AND ENVIRONMENT. A LATER STUDY OF ADOPTEES INDICATES THAT INTELLIGENCE IS THE ONLY FACTOR WHICH CORRELATES AS A RESISTANCE TO DEVELOPING CRIMINALITY IN A HIGH RISK GROUP OF ADOPTEES WITH BOTH CRIMINAL BIOLOGIC AND ADOPTIVE FATHERS. TABULAR AND GRAPHIC DATA ARE PROVIDED, AS ARE REFERENCES. (DAG)