The study of twins / Peter Mittler.

  • Mittler, Peter J.
Date:
[1971]
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Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: The study of twins / Peter Mittler. Source: Wellcome Collection.

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    39 Attitudes to twins of a birth weight of five and a half pounds or under. There are also serious difficulties of delivery; over a third are 'breech' presentations, compared with three per cent of singletons, and the risk to the second-born twin is particu¬ larly great. One in six of all multiple pregnancies in Eng¬ land ends in the death of one or both twins (Dunn, 1965). There is also evidence that a 'growth retardation factor' persists into childhood. It might have been expected that twins would compensate for their low birth weight and growth retardation in later childhood, but it appears from longitudinal studies that this is not, in general, the case (Drillien, 1964). Twins are as a group well below the national norms in both height and weight and in other physical measurements. Drillien's Edinburgh survey (1964) showed that they remained below national norms for height and weight at the age of five years; similar results were obtained by Koch (1966) in Chicago, while Husén (1959) reported that Swedish twins being conscripted for military service still showed significant retardation in height and weight at the age of eighteen years. In his large and representative sample of 873 Swedish young male twins, Husén reported a mean height of 1-3 cm. below the mean of the singleton conscripts, with MZ twins being significantly shorter than DZs; a similar retardation was also found for weight. The significance of the continued growth retardation of twins goes beyond that of physical development alone. Correlations between height and intelligence test scores have been reported in several investigations - as high as 0-4 in Bayley's study (1956). Attitudes to twins Because twins have throughout history been regarded as 'different' by their fellow men, it is reasonable to speculate about the attitudes and child rearing practices of the mothers of the twins themselves, and the effects that such attitudes might have on their behaviour and development. While people in general tend to treat twins as a pair, the mother