LIGHT ON HEREDITY.

Auckland Star, 2 September 1933, Page 8 (Supplement)

LIGHT ON HEREDITY.

EXPERIMENTS WITH TWINS.

TRAITS ANB TRAINING.

"HUMAN CUTTINGS."

A group of distinguished psychologists, neurologists and educators recently attended a meeting of the Advisory Council of the Normal Child Development Clinic in New York and watched tho antics of two identical twine eleven months old—that is, twins produced from a single cell. Like all identical twins, these were of the same eex—two boye. They were designated by a nonidentifying "A" and "B." Until the ago of about nine months there was little difference between the physical and psychical attributes of the twins. Now "A" performs acts such as swimming, for which ho has been eystcmatically trained, with a, fearlessness and sense of security not displayed by his brother. Influence of Environment. The experiment is of some importance because of the controversy that rages between the eugeniste, who maintain that environment counts for little or nothing, and the Watson behavioriets, who insist that environment is everything. The truth probably lies somewhere between the two. Such traits as eye colour, stature and intellectual ability are traceable to the genes or units of heredity. But, as the twins exhibited in Now York prove, education (environment) has some influence in making us what we are. Emotional Reactions. Professor Muller, of Austin, Texas (he who created such a sensation some years ago by turning X-rays.on fruit-fly eggs and breeding monstrosities as a result), once made a study of a few identical twins which brought out how much we owe to heredity and how much to environment. Ono of his cases was that of two identical twin girls who were separated soon after their birth. At 30 their intelligence scores were almost equal, but their emotional reactions were different. Ono had married, the other had remained single; one was attracted by Catholicism, the other by Christian Science. Later work with identical twins by Professor Newman, of the University of Chicago, brings out even greater intellectual diffcrencee than Muller detected. Identical and Ordinary.

Identical twins undoubtedly carry the same particular group of genes or hereditary factors contributed by their parents. Haldanc says, "They resemble one another as do the cuttings of the same plant, whilo ordinary twine differ just ae do seedlings from the same plant, provided that it doee not belong to a pure race." Ho adds very pertinently: "If human beings could be propagated by cuttings liko applo trees, aristocracy would 'be biologically sound. England would presumably bo governed by cuttings of Cromwell and Chatham; America, as I believe Bateson once suggested, by cuttings of Washington and Lincoln."