How People Make Their Own Environments: A Theory of Genotype →Environment Effects Author(s): Sandra Scarr and Kathleen McCartney Source: Child Development, Vol. 54, No. 2 (Apr., 1983), pp. 424-435 Published by: Wiley on behalf of the Society for Research in Child Development Stable URL: http://www.jstor.org/stable/1129703 . Accessed: 01/04/2013 01:32 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp . JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Wiley and Society for Research in Child Development are collaborating with JSTOR to digitize, preserve and extend access to Child Development. http://www.jstor.org This content downloaded from 128.95.71.159 on Mon, 1 Apr 2013 01:32:53 AM All use subject to JSTOR Terms and Conditions How People Make Their Own Environments: A -- Theory of Genotype Environment Effects Sandra Scarr and Kathleen McCartney Yale University SCARR, SANDRA, and McCARTNEY, KATHLEEN.How PeopleMake Their Own Environments:A Theory of Genotype -- Environment Effects. CHILDDEVELOPMENT, 1983, 54, 424-435. We propose a theory of development in which experience is directed by genotypes. Genotypic differ- ences are proposed to affect phenotypic differences, both directly and through experience, via 3 kinds of genotype -- environmenteffects: a passive kind, through environmentsprovided by biologically related parents; an evocative kind, through responses elicited by individuals from others; and an active kind, through the selection of different environmentsby different people. The theory adapts the 3 kinds of genotype-environment correlations proposed by Plomin, DeFries, and Loehlin in a developmental model that is used to explain results from studies of deprivation, intervention, twins, and families. Introduction evolutionary theory that individual differences depend in part on genotypic differences. We Theories of behavioral have development argue that genetic differences prompt differ- ranged from genetic determinism to naive ences in which environments are environmentalism. Neither of these radical experienced and what effects they may have. In this view, views nor interactionism has ex- adequately the genotype, in both its the of or the species specificity plained process development and its individual variability, largely deter- role of experience in development. In this mines environmental effects on we a of environmental development, paper propose theory because the genotype determines the organ- effects on human development that empha- ism's to environmental sizes the role of the in responsiveness op- genotype determining portunities. not only which environments are experienced by individuals but also which environments A theory of behavioral development individuals seek for themselves. To show how must explain the origin of new psychological this theory addresses the process of develop- structures. Because there is no evidence that ment, the theory is used to account for seem- new adaptations can arise out of the environ- ingly anomalous findings for deprivation, ment without maturational changes in the adoption, twin, and intervention studies. organism, genotypes must be the source of new structures. For the species, we claim that human and its experience effects on development Maturational sequence is controlled pri- on depend primarily the evolved nature of the marily by the genetic program for develop- human genome. In evolutionary theory the ment. As Gottlieb (1976) said, there is two essential concepts are selection and vari- evidence for a role of environment in (1) ation. Through selection the human genome has maintaining existing structures and in (2) evolved to program human development. elaborating existing structures; however, there Phenotypic variation is the raw material on is no evidence that the environment has a which selection works. Genetic variation must role in (3) inducing new structures. In de- be associated with phenotypic variation, or velopment, new adaptations or structures can- there could be no evolution. It follows from not arise out of experience per se. We thank Emily Cahan, Jerome Kagan, KatherineNelson, Robert Plomin, and Theodore D. Wachs for their critical and helpful comments on several drafts of this paper. Their disagree- ments with us were stimulating and always constructive. Much of the family researchreviewed here was done in collaborationwith Richard A. Weinberg and supported by the W. T. Grant Foundation and the National Institute of Mental Health. The day-care studies have the collab- oration of J. Conrad Schwarz, Susan Grajek, and Deborah Phillips and were supported by the W. T. Grant Foundation and the Bermuda Government. Requests for reprintsshould be sent to Sandra Scarr, Department of Psychology, Yale University, Box 11-A Yale Station, New Haven, Connecticut 06520. [ChildDevelopment, 1983, 54, 424-435. @ 1983 by the Society for Researchin Child Development, Inc. All rights reserved. 0009-3920/83/5402-0026$01.00] This content downloaded from 128.95.71.159 on Mon, 1 Apr 2013 01:32:53 AM All use subject to JSTOR Terms and Conditions Scarr and McCartney 425 The most widely accepted theories of "grasped" by the person. As we all know, the development are vague about how new struc- relevance of environments changes with de- tures arise; for example, Piaget (1980) fails velopment. The toddler who has "caught on" to make the connection between organism to the idea that things have names and who and environment clear in his references to demands the names for everything is experi- interaction. Nor is development well described encing a fundamentally different verbal en- by maturation alone (see Connolly & Prechtl, vironment from what she experienced before, 1981). Neither Gesell and Ilg (1943) nor even though her parents talked to her exten- contemporary nativists (e.g., Chomsky, 1980) sively in infancy. The young adolescent who appreciate the inextricable links of nature and played baseball with the boy next door and nurture in a hierachically organized system now finds herself hopelessly in love with him of development. is experiencing her friend's companionship in a new way. We suggest that the problem of new structures in development has been extraor- A model of genotypes and environments. dinarily difficult because of a false parallel -Figure 1 presents our model of behavioral between genotype and environment, which, development. In this model, the child's pheno- we argue, are not constructs at the same level type (P,), or observable characteristics, is a of The analysis. dichotomy of nature and function of both the child's genotype (Ge) nurture has always been a bad one, not only and her rearing environment (Ec). There will for the oft-cited reasons that both are required be little disagreement on this. The parents' for development, but because a false parallel genotypes (G,) determine the child's geno- arises between the two. We propose that de- type, which in turn influences the child's velopment is indeed the result of nature and phenotype. Again, there should be little con- nurture but that genes drive experience. troversy over this point. As in most develop- Genes are components in a system that orga- mental theories, transactions occur between nizes the organism to experience its world. the organism and the environment; here they The organism's abilities to experience the are described by the correlation between world change with development and are in- phenotype and rearing environment. In most dividually variable. A good theory of the en- models, however, the source of this correla- vironment can only be one in which experi- tion is ambiguous. In this model, both the ence is guided by genotypes that both push child's phenotype and rearing environment and restrain experiences. are influenced by the child's genotype. Because the influences both Behavioral on child's genotype development depends both the and the a and a suitable environment phenotype rearing environment, genetic program their correlation is a function of the for the of the geno- expression human, species- The is for Differences type. genotype conceptually prior typical program development. to both the and the environ- can arise from phenotype rearing among people both genetic ment. and environmental differences, but the pro- cess by which differences arise is better de- It is an unconventional shorthand to -- scribed as genotype environment effects. suggest that the child's genotype can directly Like Chomsky and Fodor (1980), we pro- affect the rearing environment. What we want pose that the is the force genotype driving G- behind development, because, we argue, it is the discriminator of what environments are actually experienced. The genotype deter- mines the of the to responsiveness person Pp those environmental opportunities. Unlike c Chomsky and Fodor, we do not think that development is precoded in the genes and with merely emerges maturation. Rather, we Ec stress the role of the genotype in determining which environments are actually experienced and what effects they have on the developing person. We distinguish here between environ- ments to which a person is exposed and environments