Heritability and the Equal Environments Assumption: Evidence from Multiple Samples of Misclassified Twins
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Classically derived estimates of heritability from twin models have been plagued by the possibility of genetic-environmental covariance. Survey questions that attempt to measure directly the extent to which more genetically similar kin (such as monozygotic twins) also share more similar environmental conditions represent poor attempts to gauge a complex underlying phenomenon of GE-covariance. The present study exploits a natural experiment to address this issue: Self-misperception of twin zygosity in the National Longitudinal Survey of Adolescent Health (Add Health). Such twins were reared under one “environmental regime of similarity” while genetically belonging to another group, reversing the typical GE-covariance and allowing bounded estimates of heritability for a range of outcomes. In addition, we examine twins who were initially misclassified by survey assignment—a stricter standard—in three datasets: Add Health, the Minnesota Twin Family Study and the Child and Adolescent Twin Study in Sweden. Results are similar across approaches and datasets and largely support the validity of the equal environments assumption.
KeywordsEqual environments Twin misclassification Heritability ACE model
This research uses data from Add Health, a Program Project directed by Kathleen Mullan Harris and designed by J. Richard Udry, Peter S. Bearman, and Kathleen Mullan Harris at the University of North Carolina at Chapel Hill, and funded by Grant P01-HD31921 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, with cooperative funding from 23 other federal agencies and foundations. Special acknowledgment is due Ronald R. Rindfuss and Barbara Entwisle for assistance in the original design. Information on how to obtain the Add Health data files is available on the Add Health website (http://www.cpc.unc.edu/addhealth). No direct support was received from Grant P01-HD31921 for this analysis. This research was funded by the National Science Foundation’s Alan T. Waterman Award, SES-0540543.
- Allison DB, Kaprio J, Korkeila M, Koshenvuo M, Neale MC, Hayakawa K (1996) The heritability of body mass index among an international sample of monozygotic twins reared apart. Int J Obes 20:501–506Google Scholar
- Conley D, Strully KW, Bennett NG (2003) The starting gate: birth weight and life chances. University of California Press, BerkeleyGoogle Scholar
- Magnusson PKE, Almqvist C, Rahman I, Ganna A, Viktorin A, Walum H, Halldner L, Lundström S, Ullén F, Långström N, Larsson H, Nyman A, Gumpert CH, Råstam M, Anckarsäter H, Cnattingius S, Johannesson M, Ingelsson E, Klareskog L, de Faire U, Pedersen NL, Lichtenstein P (2012) The Swedish twin registry: establishment of a biobank and other recent developments. Twin Res Human Genet. doi: 10.1017/thg.2012.104 Google Scholar
- Plomin R, DeFries JC, McClearn GE, McGuffin P (2001) Behavioral genetics, 4th edn. Worth Publishers, New YorkGoogle Scholar
- Rist RC (1977) On understanding the process of schooling: contributions of labeling theory. In: Karabel J, Halsey AH (eds) Power and ideology in education. Oxford University Press, New York, pp 292–305Google Scholar
- Rowe DC, Jacobson KC (1998) National longitudinal study of adolescent health: pairs code book. Chapel Hill, NC, Carolina Population CenterGoogle Scholar
- Rowe D, Teachman J (2001) Behavioral genetic research designs and social policy studies. In: Thornton A (ed) America’s families and children: research needed in the coming millennium. University of Michigan Press, Ann Arbor, pp 157–187Google Scholar