Intrinsic and extrinsic religiousness: Genetic and environmental influences and personality correlates

Thomas J. Bouchard, Matt McGue, David Lykken, Auke Tellegen

Research output: Contribution to journalArticlepeer-review

92 Scopus citations


This report presents findings for the Intrinsic (IR) and Extrinsic (ER) religiousness scales from the Minnesota Study of Twins Reared Apart. The scales were shown to be internally consistent, sufficiently distinct from the scales of the California Psychological Inventory and the Multidimensional Personality Questionnaire and unrelated to a number of measures of response style to justify treating them as distinct traits. The I scales also showed considerable evidence of construct validity in its correlations with religious fundamentalism and authoritarianism as assessed by the MMPI and Altemeyer's Right-Wing Authoritarianism scale. Data on IR and ER from 35 pairs of monozygotic twins reared apart (MZA) and 37 pairs of dizygotic twins reared apart (DZA) were fitted to a biometric model and demonstrated significant heritability (0.43 and 0.39), with a model containing genetic plus environmental factors fitting significantly better than a model containing only an environmental component. Twin similarity could not be explained by placement on a self-reported measure of family Moral Religious Emphasis as measured by the Family Environment Scale.

Original languageEnglish (US)
Pages (from-to)88-98
Number of pages11
JournalTwin Research
Issue number2
StatePublished - Jun 1999

Bibliographical note

Funding Information:
Thisresearch has been supported by grantsfrom The Seaver Institute, The Pioneer Fund, The University of Minnesota Graduate School, The Koch Charitable Foundation, The Spencer Foundation, The National Science Foundation (BNS-7926654), and the Har-court Brace Jovanovich Publishing Co.


  • Personality
  • Religiousness
  • Twins


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