18G 
Mm-ellanea 
be somewhere about -o. Correlations between individuals and various aspects of their environment have 
also been worked out — as, for instance, mental ability and conditions of clothing, or between myopia and 
the age of learning to read * — and the mean value is found to be about -Ohi. It is then said that the 
mean "nature value" is at least five to ten times as great as the mean "nurture value," and upon this 
is founded the generalisation that "nature" is of far greater importance than "nurture"t- It may be 
questioned, however, whether such a comparison does not involve a serious mistake. For if we consider 
the two mean values that are compared, we find that, whereas the "mean nature value" is the mean 
value of a number of observations, all of which provide a full measure of the strength of heredity, the 
"mean nurture value" is the mean value of a number of observations, each of which measures only the 
strength of some one isolated aspect of environment. It would appear then that the full strength of 
inheritance has been compared, not with the full strength of environment, but with the average of a 
number of small isolated aspects of the latter. As a matter of fact it is quite beyond our power at 
present to sum up the full effect of environment upon the individual and compare it with the full effect 
of heredity. We are, therefore, justified in saying that we neither know in particular cases how far the 
environment can produce any effect, nor can we make any definite statement as to the comparative 
strength of "nature" and "nurture." 
Now this is the doctrine passed by the Editors of the Eugenics Review, the journal of a 
society, which has assumed the mantle of Francis Galton|, and it is passed, because the 
editorial committee of that society does not gras23 the meaning of multiple correlation ! The 
passages in italics have been so printed to draw our readers' attention to them. In the first 
place, of course, a single correlation coefficient does not pro\'ide a full measure of the strength 
of heredity. In the table cited the coefficients are those for one parent or for one brother or 
sister. Each relati\'e — and those for independent stocks are either non-correlated or inter- 
correlated very slightly — provides such a coefficient, and furthei- each character in such relatives 
may be correlated with the character under discussion in the subject in question. In the_^next 
place the environment factors do not consist of "some one isolated aspect of environment." 
All tliese factors or aspects are closely interlinked, and this was a fact well-known to the 
workers in the Galton Laboratory. The real interpretation of such a difference as '50 and "03 
in the average values of single coefficients can only be api)i'eciated by those who are conversant 
with the theory of mnltijile correlation, and it is quite clear that those who profess to guide the 
public in this very difficult problem — which is essentially a scientific problem— lack any adequate 
knowledge of the sole instrument by which any conclusion can be drawn. 
The writer appears to be wholly ignorant of the nature of multiple correlation in the first 
place, and in the second entirely to overlook the very high correlations which exist between 
environmental factors. Bad wages, bad habits, bad housing, uncleanliness, insanitary sur- 
roundings, crowded rooms, danger of infection, etc., etc. are all closely associated together, 
and while the order of correlation between environmental and physical characters is low, that 
between individual environmental factors is in our exjierience very high. Thus the i^roblem of 
multiple correlation illustrates closely the theory developed in the first part of this note ; we 
have to deal with a low p and a high €. 
For example, if we take the environmental factors to have an average inter-correlation of '70, 
then an infinity of such factors for a mean environmental and individual correlation of -03 would 
* As the writer phrases this correlation, it is very liable to be misinterpreted. What the Galton 
Laboratory did was to show that myopia was very markedly inherited, and that the theory that it was 
largely due to school environment was incorrect, because children who began to read late, i.e. went late 
to school, were not less myopic than those who went early. 
t Karl Pearson, Nature and Nurture, Eugenics Laboratory, Lectures vi. p. 25. 
X If there was one point on which Francis Galton felt strongly and wrote it was on this point of the 
relatively great intensity of "nature" as compared with "nurture." I do not stand alone in recognising 
it as an essential part of his teaching : " I am inclined to agree with Francis Galton," writes Charles 
Darwin, "in believing that education and environment produce only a small effect on the mind of 
anyone, and that most of our qualities are innate." 
