MISCELLANEA. 
I. Inheritance of Psychical Characters. 
By KARL PEARSON, F.R.S. 
In view of the papers that have been pubhshed on the inheritance of intelligence, it is 
strange that there should still remain any doubt that psychical characters are inherited at the 
same rate as physical characters. But having regard to the existence of that douVit any material 
bearing on the point deserves special recognition and emphasis. 
In a recent contriliution to the Journal of Delinquency^ Vol. iv. p. 46, Dr Kate Gordon gives 
the results of her tests by the Binet-Simon method of the intelligence of the children in three 
orphanages in California. Among other data she gives, almost as an aside, a small table for 
the correlation in intelligence-quotients of 91 jiairs of siblings. This talile appears to me 
of very considerable interest and supj)lies what is occasionally lacking, a nearly uniform environ- 
ment* both in training and in nourishment to the pairs dealt with. Those who dislike the 
idea that the mental as well as the physical characters are largely fixed for us l:>y our ancestry 
are apt to attribute — regardless of known measurements of the intensity of environmental 
influence — the correlation of jiairs of siblings for mental characters to a differential environment 
of the pairs, i.e. to differential family or home training. Hence the value of data obtained 
within the walls of an orphanage, as tending to minimise this differentiation. 
The Intelligence Quotient, it will be remembered, is the ratio of the mental age as given by an 
intelligence test of the Binet-Simon type to the actual age. The accompanying cori'elation table 
is the 'scatter' table of Dr Gordon rendered symmetrical, so that we can enter with either nieml>er 
of the pair. The jirobable error must, of course, be calculated for the correlation on the basis of 
91 pairs, but for the mean and standard-deviation on 182 individuals. We find : 
Mean Intelligence Quotient =92-857 ± -8.%, 
Variability in Intelligence, s.D. ... ... =16-727 ±'591, 
Coefficient of Variation ... ... ... =]8'014 ±'657, 
Correlation of Intelligence between Siblings r= -5082 + •0524. 
At first sight it might seem as if the mean Intelligence Quotient was somewhat low. For a 
normal child it should be theoretically 100, but so much dejtends on the nature of the tests 
used and also on the manner in which they are applied that we cannot dogmatise on this point. 
In some recent American data we found a very low intelhgence quotient among literate adults, 
and the result was clearly due to the nature and method of applying the test. The coefficient 
of variation in this case rose to the high value of 38-52, fully double the value we have found in 
other cases. We may note that the coefficient of variation is also large in the present case, 
which is distinctly against intelligence being nuich influenced by environmental conditions — 
* The ideal method would be to take all the siblings in a very large orphanage, such for example as 
the Keedham asylum, and select if the numbers should prove adequate only the children who had 
entered the orphanage at an early age. 
