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Cotwin Closeness in Monozygotic and Dizygotic Twins: A Biasing Factor in IQ Heritability Analysis?

Published online by Cambridge University Press:  01 August 2014

K. Tambs ,
J. M. Sundet  and
K. Berg
K. Tambs*
Affiliation:
Institute of Psychology
J. M. Sundet
Affiliation:
Institute of Psychology
K. Berg
Affiliation:
Institute of Medical Genetics, University of Oslo
*
Institute of Psychology, Box 1094, Blindern, Oslo 3, Norway

Abstract

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For 98 pairs of MZ twins, four measures indicating degree of cotwin closeness were correlated with absolute differences between IQ scores within pairs. In two different twin samples (40 MZ vs 40 DZ pairs and 169 MZ vs 174 DZ pairs, respectively), means and standard deviations in the closeness variables were obtained for MZ and DZ pairs. Whereas MZ cotwins were clearly closer than DZ cotwins, the relation between cotwin closeness and similarity in IQ seemed rather weak and ambiguous. “Years lived together in childhood home” were positively related to similarity in IQ (P < 0.01), whereas subjective feeling of closeness in contact tended to be negatively related to similarity in IQ.

Keywords

IQ and environmentTwin methodEnvironmental similarity in twins
Type
Review Article
Information
Acta geneticae medicae et gemellologiae: twin research , Volume 34 , Issue 1-2 , April 1985 , pp. 33 - 39
Copyright
Copyright © The International Society for Twin Studies 1985

References

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