“The knowledge that so many of the criminal youths are abnormal is indeed very significant for the therapeutic treatment of the social offenders, for the choice of the ways which should be used to improve the youths; but this knowledge has no significance for establishing the causes of delinquency.... The abnormal parents really have more children who are abnormal and under the average in capacity, but their children are actually more seldom delinquent because of the natural tendencies than the children of normal parents” (_121_). Healy has followed a similar plan in subjectively weighing the influence of various factors as causes of the delinquency of 823 recidivists before the Psychopathic Institute at the Chicago Juvenile Court. Although he does not directly estimate hereditary and environmental factors as such, his summary of these estimates of separate cases shows the main cause of delinquency in 455 of these cases to be some form of mental abnormality or peculiarity. Abnormal physical conditions, including excessive sex development accounted for 40 more. His other causes, which embraced only 26% of the cases, might possibly be regarded as directly environmental. They included defective home conditions, including alcoholism, bad companions, mental conflicts, improper sex experience and habits, etc. Thus we find that the two most important expert estimates of individual cases after exhaustive study apparently agree in placing the main causal influence on factors which are predominately inner rather than outer. The most serious objection to this method of approaching the problem is that we have no way of determining how far such a result is the effect of the expert's unintentional bias. Gruhle's analysis of his delinquent group, however, raises very clearly the question whether the total influence of heredity may not be markedly greater in the production of delinquency than merely the heredity influence through mental deficiency and abnormalities in the families. A better method of evaluating the relative influence of heredity and environment would avoid the danger of subjective bias by studying objectively measured factors. With either the subjective or objective method correlation affords a better way of statistically handling the results. The best approach to an objective study of the inner and outer causes of delinquency by the correlation methods is furnished by Goring. The ingenuity of the biometrical procedure in applying correlation to resolving this perennial question of heredity and environment must be recognized by all who take the time to understand its methods. We can only briefly consider the results of Goring's chapter on “The Relative Influence of 'Inheritance' and 'Contagion' upon the Occurrence of Crime and the Production of Criminals.”