CHAPTER III

HEREDITY AND ENVIRONMENT

WHETHER heredity or environment is the more important factor is a question which has been much debated, and this often without any consideration being given by the disputants as to the meanings which they wish to be attached to any of the words they use, to 'heredity,' to ' environment,' or to 'importance.' Moreover, it is but seldom that any trouble is taken to inquire in what way importance can be measured numerically; though, without some method of measurement, it is obviously impossible to prove that the importance of one thing is greater than that of another. Again it is impossible to discuss with precision the importance in the abstract of any factor, because to do so leaves undecided the question as to whom the importance of that factor is supposed to be attached. In view of all this uncertainty, it is little wonder that such debates are nearly always quite futile.

Literally inheritance means that which is acquired by an heir from his ancestors; and in ordinary conversation the word is usually used in connexion with material possessions received from some relative; a meaning which is occasionally so extended as to make it cover all that a man acquires from his home or early associations, either by education, tradition, or mere contact with those about him in youth. On the other hand the student of science, intent on physical structure and mental and bodily development, is apt to associate the word 'inherit,' and all its derivatives, exclusively with the extent to which a man's bodily and mental qualities can be explained or accounted for by reference to his blood relationship with his ancestry; and it is in this connexion that the word 'heredity,' at all events, will here always be used.

When confusion is likely to arise because of such widely different meanings having been attached to the same words, 'natural inheritance' will be used to indicate all that is received from its parents by an infant solely on account of its physical descent from them; whilst under ' environmental inheritance' will be included all that a man acquires on account of his home surroundings and early training.

At the risk of being tediously elementary, it may be as well to illustrate more fully what are the factors which under the titles of ' heredity' and 'environment' are here being compared. Let us imagine, in the first instance, two human beings subject throughout the whole of their lives to absolutely the same influences, moral, intellectual, educational, and physical-two men, in fact, who have always lived in exactly the same environment. These two individuals would certainly be easily distinguished the one from the other; and the differences between them, which in these circumstances could not be due to the effect of any external conditions, may be described as their inborn, inherent, or naturally inherited qualities. Imagine, on the other hand, a pair of twins springing from identical germs and therefore destined, in the absence of all external causes of difference, to be absolutely like each other in every cell of their bodies and every element of their minds. In this case also, differences would become apparent when the twins had grown up; because the environment to which they would by then have been exposed certainly would not have been exactly alike in the two cases; and the resulting differences between them, which could have no relation to any differences in their original potentialities or predispositions, may be called their acquired characters. It must, however, be confessed that this nomenclature can only be recommended on the ground that it is commonly used, and not because it corresponds to any clear division of human characters. No man is born into the world without naturally inherited tendencies affecting every element of his mind and body; to be without an environment is inconceivable, and no one can escape from the effects

of the surroundings to which he has been exposed; and, consequently, in every part of him, man is always subject to the influence both of heredity and of environment. We might at first sight be inclined to cite the scar of a wound as being a purely acquired character; but the same wound would mark two men differently as the result of differences in their inborn qualities. Again, the colour of a man's eye may fairly be described as a natural inheritance, because that colour would have been much the same however different had been his previous surroundings. We must not forget, however, that without a sufficiently suitable environment, neither the man nor his eyes could have come into existence. We shall be on safer ground, in fact, if in this connexion we speak of differences rather than of qualities; if we describe a scar as an acquired difference, by means of which an injured man may be distinguished from a man without such a scar; and if such characteristics as the colours of the eyes are classed as hereditary differences, or more accurately as differences dependent on natural inheritance. Comparatively few of the differences which distinguish one man from another can, however, without qualification be classified or described as hereditary or acquired; for we must always remember that all human qualities or characters are the result of environment, or an external factor, acting on the hereditary tendencies or potentialities of the individual in question.

Granted that we are always dealing with heredity and environment when studying the qualities of human beings, how is it possible for us to disentangle the effects of these two factors? Perhaps the nature of their interdependence, and the limitations which that interdependence places on the possibility of drawing comparisons between them, may be in a measure illustrated by the following analogy; though, like most analogies, it is faulty in several respects. If a man weighs 15 stone, it cannot be said that so many pounds of his weight are due to his height and so many to his girth; and, in the same way, taking, for example, the case of a thousand paupers, it is useless to ask in how many cases can their pauperism be solely

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attributed to environment and in how many only to their innate qualities. Such a question is meaningless, because the idea of a pauper either without an environment or without natural or inborn tendencies is inconceivable. But, in the case of almost every man, there will come a period in his life when no further change in his weight will occur on account of a change in his height, although his weight will be only too likely to increase as the result of other alterations in the shape of his body. Just as changes in weight, resulting from changes in height, can be considered independently of changes in weight due to changes in girth, so differences in all human qualities, mental and bodily, may be considered under two headings, namely those due to differences in past surroundings and those due to differences in innate susceptibilities. From this it follows that when we can measure the change both in a man's height and in his girth, we can associate or correlate the change in his weight with each of these two factors separately. In like manner if we could actually measure the differences in the surroundings to which the different individuals composing any group of persons had been exposed, and also the differences in their innate susceptibilities or original potentialities, then we could correctly associate or correlate these differences with the differences of their environments and of their heredity respectively. Unfortunately we cannot get at the human germ before its development commences and, even if we could do so, its qualities would not be measurable by us. Problems connected with the differences between hereditary and environmental effects must always be attacked by some far more indirect method than this.1

1 It should perhaps here be noted that we can only correlate differences in qualities with differences in either hereditary or environmental factors; we cannot simply divide these differences between these two factors. If a man weighing 10 stone increases 10 per cent. in height, it might be said that he will increase 1 stone in weight in consequence. If the same man also increases 10 per cent. in width, apparently he will add another stone to his weight on this account also, making his weight 12 stone in all. But actually he will be found to have increased to 12 stone and one-tenth; for 11 x 11 = 121. To which is this odd tenth of a stone to be attributed, to a change in his height or a change in his width? Again it should be noted that my analogy is misleading in the following

Even in scientific literature the advantages to be derived from discussing the differences between the qualities of human beings rather than the qualities themselves has often been insufficiently recognized; and we are, therefore, led to inquire what is the meaning intended to be conveyed by the words 'quality' and 'character' when used in connexion with problems of heredity, these terms often being employed synonymously. Ought we to define 'quality' as an attribute by means of which different classes of things can be distinguished from each other? Accepting this definition, the wearing of a black coat or being close shaven must unquestionably be included amongst human qualities; a conclusion with which no biologist would agree. Should we narrow down the definition of quality so as to make it exclude all attributes except such as are both measurable and actually relate to the bodies or minds of the individuals in question ? If so, certain attributes closely correlated with differences of environment, such as being sunburnt, and certain effects of education on the mind, such as knowing how to speak French, would still have to be described as qualities or characters. But in discussing such matters, do we not rather prefer to regard the human 'qualities in question as consisting in the readiness or tendency of the skin to become sunburnt, and in the facility with which any foreign language can be acquired? The biologist, at all events, seems to desire to exclude as far as possible from the meaning of these terms all reference to the effects of external circumstances. But if, in deference to this view, we still further narrow our definition, and if 'qualities' or 'characters' are held only to comprise those differences between human beings which are independent of environmental influences, then anyone declaring that all our qualities are entirely innate would be fully respect. A man is becoming sunburnt because he is exposed to a hot sun; he is not exposed to the sun because he is being sunburnt. There is no doubt which is cause and which is effect. In many social problems, however, we remain in complete doubt as to which is cause and which is effect. But we can always correlate or associate changes or differences with each other without discussing the question of cause and effect.