38 
GENETICS: C B. DAVENPORT 
wanting those who have insisted that 'criminahty is hereditary' yet no 
one has successfully determined the method of such inheritance. It 
appears, indeed, improbable that so complex a thing as criminality 
should prove to have a single hereditary factor. An attempt has been 
made to study the hereditary behavior of some of the elements of moral 
action — to analyze the family history of persons who have marked 
emotional traits. 
Opportunities for such study have been afforded by 165 family histories 
of wayward girls in state institutions gained by trained field workers 
who visited the homes of the patients and got as full an account as possible 
of the behavior of all of the close relatives. The data were gathered 
without prejudice; indeed, it was impossible for the 'field worker' to know 
what laws of inheritance the histories might yield. Also, many other 
sources of information at the Eugenics Record Office have been drawn 
upon for additional data as to the inheritance of special traits. 
Violent and more or less periodic outbursts of temper occur in families 
which are characterized by prevalence of epileptic attacks, also in those 
exhibiting cases of mania, also in others in which 'hysterical' attacks are 
common. The special form of the attacks differs somewhat in these 
classes of famiHes, but the method of inheritance of the tendency is the 
same in all, and it seems probable that in each class the simple s3anptoms 
of the emotional outburst are modified by the differences in these three 
classes of the nervous condition. 
The method of inheritance is indicated at once by the fact that, in 
the 66 family histories studied, the tendency to outbursts does not, typi- 
cally, skip a generation. In one history it is traced through 5 generations ; 
in a large proportion of the histories it is traced through 3 consecutive 
generations. The few cases in which neither parent of an affected 
individual is reported to have the tendency to outbursts are explained 
by obvious insufficiency in the record. 
The fact that the tendency to outbursts of temper does not skip a 
generation indicates that it is a positive or dominant trait. That segre- 
gation of this tendency occurs is shown by the ratio of affected offspring 
in any fraternity to the total number of offspring whose emotional history 
is fully described. From the mating of an uncontrolled and a normal 
person expectation is that 50 percent of the children will be imcon trolled. 
A summation of all such children gives a total of 106 affected among 
219 sufficiently described, or close to the 50 percent expected on the hy^o- 
thesis that the tendency to outbursts of temper is a simple, positive trait. 
The detailed investigation will appear in the Journal oj Nervous and 
Mental Diseases and in the Bulletin of the Eugenics Record Office. 
