However, age appeared to have some influence, and the youths reared in homes with mothers only committed a substantially higher rate of violent crimes than did the youths reared in other types of family settings. The subjects were all incarcerated in the institution between January 1980 and December 1981. Their average age was 15.7 years, and they had completed an average of 7.67 grades in school. The average IQ was 79.29. Just over half had committed nonviolent crimes; 44 percent were reared by the mother only. Just under half lived in areas under 50,000 in population; the rest lived in more populous areas. Factors not considered in the study probably affected the rates of violent crimes committed. Data tables and 47 references are supplied.