THE SAMPLE OF 1,145 MALE ADOPTEES STUDIED WAS TAKEN FROM AN ESTABLISHED FILE OF 5,483 ADOPTEES, ENCOMPASSING ALL NONFAMILIAL ADOPTIONS IN THE CITY AND COUNTY OF COPENHAGEN, DENMARK, BETWEEN 1924 AND 1947. ADOPTEES IN THE SAMPLE WERE BORN BETWEEN JANUARY 1, 1927 AND DECEMBER 31, 1941. SINCE THE STUDY WAS CONDUCTED IN 1971, ALL SUBJECTS HAD PASSED THROUGH THE GREATER PART OF THE RISK PERIOD FOR CRIMINALITY. FOR PURPOSES OF COMPARISON, THE SAMPLE ADOPTEES WERE MATCHED INDIVIDUALLY WITH A GROUP OF NONADOPTEES FOR SEX, AGE, OCCUPATIONAL STATUS OF THEIR FATHERS, AND RESIDENCE. INDIVIDUALS IN THE CONTROL AND EXPERIMENTAL GROUPS WERE CHECKED FOR REGISTRATION IN THE POLICE FILES. THE CRIMINALITY OF THE ADOPTIVE AND BIOLOGICAL FATHERS OF THE ADOPTEES AND THE FATHERS OF THE NONADOPTED CONTROLS WAS ALSO CHECKED THROUGH POLICE FILES. COMPARISON RESULTS INDICATE AND ASSOCIATION BETWEEN THE CRIMINALITY OF THE SONS AND THEIR FATHERS IN APPROXIMATELY THE SAME DEGREE AMONG BOTH ADOPTEES AND NONADOPTEES. WITH THE ADOPTEES, IT APPEARS ON BOTH THE BIOLOGICAL AND ADOPTIVE FATHERS' SIDE. A PROBAND STUDY WAS MADE FOR A CLOSER EXAMINATION OF THE RELATIVES OF A CRIMINAL GROUP AND TO COMPARE THEM WITH THE RELATIVES OF A MATCHED NONCRIMINAL GROUP. A GROUP WAS SELECTED FROM THE 185 CRIMINAL ADOPTEES TO INCLUDE ALL THOSE CASES IN WHICH THE BIOLOGICAL FATHERS WERE IDENTIFIABLE AND WHOSE ADOPTIVE AND BIOLOGICAL FATHERS WERE BORN IN AND AFTER 1890. THESE 143 CRIMINAL ADOPTEES BECAME THE INDEX PROBANDS, AND THEY WERE MATCHED INDIVIDUALLY WITH 143 ADOPTEES WHO WERE NOT KNOWN TO THE POLICE, THUS BECOMING THE CONTROL PROBANDS. MATCHING WAS MADE ON THE BASIS OF AGE AND OCCUPATIONAL STATUS OF THE ADOPTIVE FATHER. THE DATA FOR THE INDEX AND CONTROL GROUPS WERE SUBMITTED TO A STEPWISE MULTIPLE REGRESSION ANALYSIS, WITH THREE FACTORS CONTRIBUTING SIGNIFICANTLY TO THE ANALYSIS -- CRIMINALITY IN AT LEAST ONE ADOPTIVE PARENT, AND PSYCHIATRIC DIAGNOSIS FOR THE THE BIOLOGICAL MOTHER. CROSS-FOSTERING ANALYSIS WAS CONDUCTED ON 1,145 ADOPTEES TO SHOW A DIFFERENCE IN THE INFLUENCE OF BIOLOGICAL AND ADOPTIVE CRIMINAL FATHERS ON CRIMINAL ADOPTEES WHICH, WHILE FALLING SHORT OF STATISTICAL SIGNIFICANCE, INDICATES THE PROMINENT INFLUENCE OF THE BIOLOGICAL FATHERS' CRIMINALITY. THE OVERALL CONCLUSION OF THE STUDY IS THAT THERE IS A CORRELATION BETWEEN CRIMINALITY IN ADOPTEES AND CRIMINALITY IN THER BIOLOGICAL PARENTS. TABLES OF DATA AND RESULTS ARE INCLUDED. (RCB)