484 EVOLUTION, GENETICS, AND EUGENICS 



in available form, it would doubtless constitute a most valuable con- 

 tribution to the study of human heredity. The twin method is a new 

 one and not yet so well established as the others, but it is growing in 

 favor every year. 



in. CRIME AND DESTINY 



One of the most remarkable uses of the twin method in the study 

 of heredity has to do with the problem of the heredity of criminal 

 tendencies. Professor Johannes Lange, of Munich, has recently re- 

 ported the results of many years of work on the criminal records of 

 twins one or both of whom had been in Bavarian prisons or reforma- 

 tories. This work was a part of the program of research of the Ba- 

 varian Institute for Criminal Biology, and is held in high esteem by 

 leaders in the field. Lange's book entitled Crime and Destiny reports 

 in some detail the criminal records of thirteen pairs of identical twins 

 and seventeen pairs of fraternal twins, one or both members of a pair 

 being in every case a confirmed and inveterate criminal. But what 

 about the other twin in the two groups? The answer to this question 

 is astonishing. Of the thirteen pairs of identical twins, there were ten 

 cases in which the other twin of the pair was also an equally confirmed 

 criminal. Not merely this, but the twin criminals of each pair ex- 

 hibited the same types of criminality: both were swindlers, both 

 thieves, both sex-offenders, both drunken ne'er-do-wells, etc., though 

 in no case were the two members of a pair associated in their crimes. 

 Of the three pairs of identical twins in which only one was a criminal, 

 there were two cases in which one member of the pair had suffered a 

 serious head injury at birth or in infancy, which might well have been 

 responsible for his criminal tendencies, while in the remaining case one 

 twin suffered severely from a goiter which might have profoundly 

 affected his conduct. From Lange's description of the last case, how- 

 ever, it seems highly probable to me that this case is incorrectly 

 diagnosed as identical, but Lange leans over backward in his attempt 

 to weight the evidence against the conclusion that criminal tendencies 

 are hereditary. 



In contrast with this impressive study of identical twins, is that 

 of the seventeen cases of fraternal twins, of which there were only 

 two cases in which both members of a pair were criminal, and these 

 exhibited relatively mild forms of criminality, such as might not have 

 appeared at all in a more favorable environment. 



In one of the cases of identical twins, both of whom were criminal, 

 one twin, after a long criminal record, married a good woman of strong 



