When we ask what causes people to commit crimes, there are always two important factors: the dispositional and situational determinants of anti-social behavior, Each hum an being is a biological organism Jiving in a social con text, and thus this behavier is always the joint outcome of hereditary and environmental influences. When we speak of hereditary factors playing a role in anti-social behavior, it is always understood that such factors alone do not cause deviant actions, but, rather, that :they increase the likelihood of such actions taking place under certain environmental conditions. Possible causes of aberrations are gene mutation, radiation, nondisjunction, drugs, viruses and geographic and possibly economic factors (Grossman, 1973) Chromosomal abnormality provides an interesting case of the possibility of a close relationship between heredity and personality. There is a higher than normal frequency. of abnormal chromosomal combinations among criminals. That is, instead of the normal female xx chromosome or the normal male xy chromosome there are supernumerary y’s such as xyy, xy yy, or xxx, of course, xyy / xyyy, xy /xyy Or xI/xyy and xo/xyy occur. Adult male prisoners who have the xyy chromosome are unusually tall, are below normal in intelligence, and. have had excessive acne during adolescence. But an abnormal chromosome does not make a criminal-some who are not criminal have the abnormal chromosome and vice versa (Moritagn. 1968) The resort to brawn rather than brain is not limited to individuals endowed with an extra y chromosome. Most violent crimes arecommitted by chromosomally normal individuals However, the high frequency with which individuals with xyy chromosomes commit crimes of violence leaves little doubt that in some cases the additional y chromo¬some exerts a preponderantly powerful influence in the genesis of oppressive behavior, (Montagu, A., 1968) Although we are in no positron to control, the genetic inheritance of an individual, we can do a great deal to change certain environmental conditions that may encourage the xyy individual to commit criminal acts. A society does not properly acquit itself of its responsibilities if it places the entire burden of caring for abnormal individual upon the parent. What we are talking about here is not a program of engenic control, but a program of social therapy. The discovery of chromosomal abnormalityas being related to criminal tendencies is fortunate if society is warned to provide an especially healthful environment for the unfortunates-but then such should be the birthright of all children.