Comment on Dr Gifford's Paper1

The paper presented by Dr Gifford and his associates is a report of the longitudinal study of a pair of identical twins, conducted with painstaking exactitude during a period of more than four years. Dr Gifford's team began their study of the twin girls when these were three months old. The team used protocolled monthly observation periods, films, tape-recorded interviews with the parents, etc. At regular intervals the collected material and the method of its collection was critically discussed. The present report covers the period up to the time when the twins were four and a half years of age.

The data thus collected are of absorbing interest. This interest is further increased and rendered particularly exciting through the presence of striking differences in personality, character, and behaviour between the twins, notwithstanding the fact that gross and microscopic examination of the foetal membranes showed them to be unequivocally monozygotic. Tradition, widespread popular and also quasi scientific belief is exceedingly vocal in the assertion that in monozygotic twins heredity produces a similarity of a nearly mystical or even occult nature in development and behaviour. A huge part of this host of traditional belief may be relegated to the category of prejudice and superstition in view of Gifford's findings.

Before discussing Gifford's data, I wish to mention a minor point: the authors suggest a revision of Freud's proposition on congenital ego variations and of Hartmann's proposition on innate maturational tendencies. They recommend that these propositions should be extended to include prenatal experience. That is a suggestion with which I agree all the more as I have also advanced it, approximately twelve years ago, though not with the same amount of precise observational justification. Nevertheless, I have kept repeating it since, suggesting that we distinguish from each other, within the concept of the 'congenital', first of all genetic influences,