Behavior Genetics

, Volume 14, Issue 6, pp 579–585

Effects of inbreeding on Raven Matrices


  • Nirupama Agrawal
    • Department of PsychologyUniversity of Rajasthan
  • S. N. Sinha
    • Department of PsychologyUniversity of Rajasthan
  • Arthur R. Jensen
    • School of EducationUniversity of California

DOI: 10.1007/BF01068128

Cite this article as:
Agrawal, N., Sinha, S.N. & Jensen, A.R. Behav Genet (1984) 14: 579. doi:10.1007/BF01068128


Indian Muslim school boys, ages 13 to 15 years, whose parents are first cousins, were compared with classmates whose parents are genitically unrelated on the Raven Standard Progressive Matrices, a nonverbal test of intelligence. The inbred group (N=86) scored significantly lower and had significantly greater variance than the noninbred group (N=100), both on raw scores and on scores statistically adjusted to control for age and socioeconomic status. Genetic theory predicts both of these effects for a polygenic trait with positive directional dominance.

Key Words

inbreeding depressionintelligenceRaven matricesheritabilitypolygenic theory
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© Plenum Publishing Corporation 1984