approximately their relative influence, are all in substantial agreement. The first light thrown on this question comes from Galton's "History of Twins,"[1] published as long ago as 1883. The traits under discussion were physical resemblances, diseases, mannerisms of action, mental disposition, temperament and tastes. The data are not given in completeness, nor in statistical form, but the conclusion seemed to him warranted that, as regards such mental and physical differences as were under discussion, nature prevails strongly over nurture, within the limits which Galton is careful to assign to the latter. This belief was arrived at from a comparison of thirty-five pairs of very similar twins with twenty pairs of dissimilar twins.
Those twins who were similar when young remained so in general, as they grew older; but more significant than this, there appeared to be no tendency for similarities in education and home life to render those originally unlike any more similar with advancing years. The conclusion from Galton's "History of Twins" seemed to be that if the environmental differences are slight no appreciable effect is produced at least upon innate mental differences which are themselves comparatively slight or unimportant, such as differences in tastes, temperament and disposition. This would of course not prove that the more important human differences, such as are represented by success or failure, vices and virtues, are not profoundly modified by environment if the differences in surroundings are considerable.
The history of royalty offers just these remarkably wide differences of an environmental nature. This is somewhat surprising because one might assume that the surroundings would be uniformly superior, as all are of the highest social rank. But for various reasons the individuals have developed under the greatest variety of good and bad influences as regards the atmosphere of their home life, their educational advantages, and opportunities for distinction. Besides, they have lived in different countries and in different eras. Yet, in spite of the fact that the environments show wide variations, these appear to be negligible factors in the production of successful achievement or in the creation of virtuous or vicious types.
That successful achievement is almost entirely due to differences in germ-plasm and is little influenced by environment is the necessary conclusion from the complete analysis of two separate groups of royalty. One of these is the great interrelated group of 3,312 distinct persons in Lehr's Genealogy. This book contains many repeated names, because the same individual appears as an ancestor of different lines, owing to intermarriages. Thus the total number of cases for statistical purposes is much greater than 3,312. It is in fact 32,768, for this book contains eight "families" with 4,096 in each family. Out of the 3,312 different persons there were sixteen who came up to
- ↑ "Inquiries into Human Faculty," 1883, pp. 216-243.
