Increased heritability for lower IQ levels?

J. Michael Bailey*, William Revelle

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Detterman et al. (1990) presented evidence based on twins that the heritability of IQ may be higher in the lower part of the IQ range. We first offer an alternative test for differential heritability across the IQ range, based on the analysis of absolute intrapair differences of monozygotic versus dizygotic twins. We then review two previous studies, each containing more twins than the sample of Detterman ea al., which examined the distribution of intrapair absolute differences. In contrast to the study of Detterman et al., both yielded results more compatible with higher heritability in the upper range of IQ. We discuss various interpretations of these findings and show how our proposed test might aid in distinguishing among them.

Original languageEnglish (US)
Pages (from-to)397-404
Number of pages8
JournalBehavior Genetics
Issue number4
StatePublished - Jul 1 1991


  • environment
  • heritability
  • intelligence
  • twins

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics
  • Genetics(clinical)


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