title: Twin Differentiation of Cognitive Ability Through Phenotype to Environment Transmission: The Louisville Twin Study.
abstract: 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.
authors.affiliation: Departments of Psychology and Gerontology, University of Southern California, 3620 South McClintock Ave., Los Angeles, CA, 90089-1061, USA. crb8v@virginia.edu.
authors.forename: Christopher R
authors.identifier: http://orcid.org/0000-0001-6827-409X
authors.initials: CR
authors.lastname: Beam
authors.affiliation: University of Virginia, Charlottesville, VA, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Turkheimer
authors.affiliation: Northeastern University, Boston, MA, USA.
authors.forename: William T
authors.initials: WT
authors.lastname: Dickens
authors.affiliation: University of Louisville, Louisville, KY, USA.
authors.forename: Deborah Winders
authors.initials: DW
authors.lastname: Davis
mesh_terms: D000293:Adolescent; D002648:Child; D002657:Child Development; D002675:Child, Preschool; D005260:Female; D059647:Gene-Environment Interaction; D006801:Humans; D007223:Infant; D007360:Intelligence / Q000235:genetics*; D008297:Male; D008957:Models, Genetic; D010641:Phenotype; D014429:Twins, Dizygotic / Q000235:genetics; D014430:Twins, Monozygotic / Q000235:genetics
keywords: Cognitive development; Genetic simplex; Intelligence; Louisville Twin Study; Nonshared environment