Encyclopedia of Clinical Neuropsychology

2018 Edition
| Editors: Jeffrey S. Kreutzer, John DeLuca, Bruce Caplan

Twin Studies

  • Rohan PalmerEmail author
  • Martin Hahn
Reference work entry
DOI: https://doi.org/10.1007/978-3-319-57111-9_1864


A research design used to determine the extent to which genetic and environmental factors contribute to variation in a population of twins.

Current Knowledge


Twin studies determine the extent to which individual differences (variation) on a particular phenotype are attributable to genetic differences between individuals (heritability). The basic tenets of twin studies originate from Ronald Fisher’s 1918 paper which demonstrated that by assuming a normally distributed liability for any given phenotype, genetic differences across multiple loci, acting additively, contribute to the variation in that trait. Consequently, the similarity or dissimilarity between pairs of relatives is attributable to genes and environments shared or not shared between them, respectively. Numerous twin studies have indicated that psychiatric and behavioral disorders are genetically influenced (Boomsma et al. 2002). For example, in a recent twin study by Young et al. (2006) the results...

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References and Readings

  1. Boomsma, D., Busjahn, A., & Peltonen, L. (2002). Classical twin studies and beyond. Nature Review Genetics, 3(11), 872–882.CrossRefGoogle Scholar
  2. Neale, M. C. (1999). MX: Statistical modeling (5th ed.). Richmond: Department of Psychiatry.Google Scholar

Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Institute for Behavioral GeneticsUniversity of Colorado at BoulderBoulderUSA
  2. 2.Department of BiologyWilliam Paterson UniversityWayneUSA