The Impact of Variation in Twin Relatedness on Estimates of Heritability and Environmental Influences
- 544 Downloads
By taking advantage of the natural variation in genetic relatedness among identical (monozygotic: MZ) and fraternal (dizygotic: DZ) twins, twin studies are able to estimate genetic and environmental contributions to complex human behaviors. Recently concerns have been raised about the accuracy of twin studies in light of findings of genetic and epigenetic changes in twins. One of the concerns raised is that MZ twins are not 100% genetically and epigenetically similar because they show variations in their genomes and epigenomes leading to inaccurate estimates of heritability. This article presents findings from a simulation study that examined the degree of bias in estimates of heritability and environmentality when the genetic and epigenetic similarity of MZ twins differs from 1.00 and when the genetic and epigenetic similarity of DZ twins differs from 0.50. The findings suggest that in the standard biometric model when MZ or DZ twin similarity differs from 1.00 or 0.50, respectively, the variance that should be attributed to genetic influences is instead attributed to nonshared environmental influences, thus deflating the estimates of genetic influences and inflating the estimates of nonshared environmental influences. Although estimates of genetic and nonshared environmental influences from the standard biometric model were found to deviate from “true” values, the bias was usually smaller than 10% points indicating that the interpretations of findings from previous twin studies are mostly correct.
KeywordsTwin studies Standard biometric model Genetic and epigenetic similarity Heritability estimate Simulation study
Compliance with Ethical Standards
Conflict of interest
Chang Liu, Peter C. M. Molenaar and Jenae M. Neiderhiser declare that they have no conflict of interest.
Human and Animal Rights and Informed Consent
This article does not contain any studies with human participants or animals performed by any of the authors.
- Bruder CE, Piotrowski A, Gijsbers AA, Andersson R, Erickson S, de Ståhl TD, … Poplawski A (2008) Phenotypically concordant and discordant monozygotic twins display different DNA copy-number-variation profiles. Am J Hum Genet 82(3):763–771. doi: 10.1016/j.ajhg.2007.12.011 PubMedPubMedCentralCrossRefGoogle Scholar
- Castorina, P., Selicorni, A., Bedeschi, F., Dalprà, L., & Larizza, L. (1997). Genotype-phenotype correlation in two sets of monozygotic twins with Williams syndrome. Am J Med Genet 69(1):107–111. doi: 10.1002/(SICI)1096-8628(19970303)69:1<107::AID-AJMG21>3.0.CO;2-S PubMedCrossRefGoogle Scholar
- Lerner RM (2004) Genes and the promotion of positive human development: Hereditarian versus developmental systems perspectives. In: Coll CG, Bearer E, Lerner RM (eds) Nature and nurture: The complex interplay of genetic and environmental influences on human behavior and development. Erlbaum, Mahwah, NJ, p. 1–33Google Scholar
- Ollikainen M, Smith KR, Joo E. J.-H., Ng HK, Andronikos R, Novakovic B, … Craig JM (2010) DNA methylation analysis of multiple tissues from newborn twins reveals both genetic and intrauterine components to variation in the human neonatal epigenome. Hum Mol Genet 19(21):4176–4188. doi: 10.1093/hmg/ddq336 PubMedCrossRefGoogle Scholar
- Plomin R, DeFries JC, Knopik VS, Neiderhiser J (2013) Behavioral genetics. Worth Publishers, New York, NYGoogle Scholar
- Reiss D, Neiderhiser JM, Hetherington EM, Plomin R (2000) The relationship code: deciphering genetic and social influences on adolescent development, vol 1. Harvard University Press, Cambridge, MAGoogle Scholar
- Veenma D, Brosens E, de Jong E, van de Ven C, Meeussen C, Cohen-Overbeek T, Tibboel D (2012) Copy number detection in discordant monozygotic twins of congenital diaphragmatic hernia (CDH) and esophageal atresia (EA) cohorts. Eur J Hum Genet 20(3):298–304. doi: 10.1038/ejhg.2011.194 PubMedCrossRefGoogle Scholar
- Weber-Lehmann J, Schilling E, Gradl G, Richter DC, Wiehler J, Rolf B (2014) Finding the needle in the haystack: differentiating “identical” twins in paternity testing and forensics by ultra-deep next generation sequencing. Forensic Sci Int Genet 9:42–46. doi: 10.1016/j.fsigen.2013.10.015 PubMedCrossRefGoogle Scholar