Behavior Genetics

, Volume 45, Issue 6, pp 622–634

Twin Differentiation of Cognitive Ability Through Phenotype to Environment Transmission: The Louisville Twin Study

  • Christopher R. Beam
  • Eric Turkheimer
  • William T. Dickens
  • Deborah Winders Davis
Original Research

DOI: 10.1007/s10519-015-9756-0

Cite this article as:
Beam, C.R., Turkheimer, E., Dickens, W.T. et al. Behav Genet (2015) 45: 622. doi:10.1007/s10519-015-9756-0


The Louisville Twin Study is one of the most intensive twin studies of cognitive ability. The repeated measurements of the twins are ideal for testing developmental twin models that allow for the accumulation of gene–environment correlation via a (P⇒E) transmission process to explain twins’ divergence in mean ability level over time. Using full-scale IQ scores from 566 pairs of twins (MZ = 278; DZ = 288), we tested whether a P⇒E transmission model provided better representation of actual developmental processes than a genetic simplex model. We also addressed whether the induced gene–environment correlation alters the meaning of the latent nonshared environmental factors with a simple numerical method for interpreting nonshared environmental factors in the context of P⇒E transmission. The results suggest that a P⇒E model provided better fit to twins’ FSIQ data than a genetic simplex model and the meaning of the nonshared environment was preserved in the context of P⇒E.


Louisville Twin Study Cognitive development Intelligence Genetic simplex Nonshared environment 

Funding information

Funder NameGrant NumberFunding Note
National Institute on Aging
  • 1F31AG044047-01A1
  • T32AG020500
  • 1R03AG048850-01
  • T32AG000037-37

Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  1. 1.Departments of Psychology and GerontologyUniversity of Southern CaliforniaLos AngelesUSA
  2. 2.University of VirginiaCharlottesvilleUSA
  3. 3.Northeastern UniversityBostonUSA
  4. 4.University of LouisvilleLouisvilleUSA

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