Article Contentsp. [1354]p. 1355p. 1356p. 1357p. 1358p. 1359p. 1360p. 1361p. [1362]p. 1363p. 1364p. 1365p. 1366p. 1367p. 1368p. 1369p. 1370p. [1371]p. 1372p. 1373p. 1374p. 1375p. 1376Issue Table of ContentsChild Development, Vol. 64, No. 5 (Oct., 1993), pp. 1299-1594Front MatterResponses to Presidential AddressThe Average Expectable Environment Is Not Good Enough: A Response to Scarr [pp. 1299 - 1317]Human Behavioral Genetics, Scarr's Theory, and Her Views on Interventions: A Critical Review and Commentary on Their Implications for African American Children [pp. 1318 - 1332]ReplyBiological and Cultural Diversity: The Legacy of Darwin for Development [pp. 1333 - 1353]Genetic Change and Continuity from Fourteen to Twenty Months: The MacArthur Longitudinal Twin Study [pp. 1354 - 1376]Multiple Perspectives on Family Relationships: A Latent Variables Model [pp. 1377 - 1388]The Interparental Relationship and Family Problem Solving with Preadolescent Males [pp. 1389 - 1400]Maternal Support Networks, Maternal Cognitions, and Young Children's Social and Cognitive Development [pp. 1401 - 1417]The Relations of Emotionality and Regulation to Preschoolers' Social Skills and Sociometric Status [pp. 1418 - 1438]Biobehavioral Organization in Securely and Insecurely Attached Infants [pp. 1439 - 1450]Linking Employment to Attachment: The Mediating Effects of Maternal Separation Anxiety and Interactive Behavior [pp. 1451 - 1460]Family Factors Related to Children's Intrinsic/Extrinsic Motivational Orientation and Academic Performance [pp. 1461 - 1474]God's Word, Religious Rules, and Their Relation to Christian and Jewish Children's Concepts of Morality [pp. 1475 - 1491]Impression Formation in Children: Influence of Gender and Expectancy [pp. 1492 - 1506]A Cognitive-Developmental Approach to Racial Stereotyping and Reconstructive Memory in Euro-American Children [pp. 1507 - 1518]Young Children's Long-Term Retention of a Pediatric Examination [pp. 1519 - 1533]Young Children's Understanding of the Mind-Body Distinction [pp. 1534 - 1549]Assumptions about Word Meaning: Individuation and Basic-Level Kinds [pp. 1550 - 1570]When Sociocognitive Transaction among Peers Fails: The Case of Misconceptions in Science [pp. 1571 - 1591]Back Matter [pp. 1592 - 1594]Genetic Change and Continuity from Fourteen to Twenty Months: The MacArthurLongitudinal Twin StudyAuthor(s): Robert Plomin, Jerome Kagan, Robert N. Emde, J. Steven Reznick, Julia M.Braungart, JoAnn Robinson, Joseph Campos, Carolyn Zahn-Waxler, Robin Corley, David W.Fulker, J. C. DeFriesSource: Child Development, Vol. 64, No. 5 (Oct., 1993), pp. 1354-1376Published by: Blackwell Publishing on behalf of the Society for Research in Child DevelopmentStable URL: http://www.jstor.org/stable/1131539 .Accessed: 24/08/2011 15:18Your 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.jspJSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact [email protected] Publishing and Society for Research in Child Development are collaborating with JSTOR to digitize,preserve and extend access to Child Development.http://www.jstor.orgArticles Genetic Change and Continuity from Fourteen to Twenty Months: The MacArthur Longitudinal Twin Study Robert Plomin The Pennsylvania State University Robert N. Emde University of Colorado Health Sciences Center Julia M. Braungart The Pennsylvania State University Joseph Campos University of California, Berkeley Robin Corley and David W. Fulker University of Colorado, Boulder Jerome Kagan Harvard University J. Steven Reznick Yale University JoAnn Robinson University of Colorado, Boulder Carolyn Zahn-Waxler National Institute of Mental Health J. C. DeFries University of Colorado, Boulder PLOMIN, ROBERT; EMDE, ROBERT N.; BRAUNGART, JULIA M.; CAMPOS, JOSEPH; CORLEY, ROBIN; FULKER, DAVID W.; KAGAN, JEROME; REZNICK, J. STEVEN; ROBINSON, JOANN; ZAHN-WAXLER, CAR- OLYN; and DEFRIES, J. C. Genetic Change and Continuity from Fourteen to Twenty Months: The MacArthur Longitudinal Twin Study. CHILD DEVELOPMENT, 1993, 64, 1354-1376. Genetic change as well as continuity was investigated within the domains of temperament, emotion, and cognition/language for 200 pairs of twins assessed at 14 and 20 months of age in the laboratory and home. The second year of life is marked by change rather than continuity: correlations from 14 to 20 months averaged about .30 for observational measures of temperament and emotion, about .40 for language measures, and about .50 for mental development. 2 types of genetic change were examined: changes in the magnitude of genetic influence (heritability) and genetic contributions to change from 14 to 20 months. In general, heritability estimates were similar at 14 and 20 months. Evidence for genetic influence on change from 14 to 20 months emerged for several measures, implying that heritability cannot be equated with stability. Analyses of conti- nuity indicated that genetic factors are largely responsible for continuity from 14 to 20 months. It must be borne in mind that the divergence of development, when it occurs, need not be ascribed to the effect of different nurtures, but it is quite possible that it may be due to the appearance of qualities inherited at birth, though dormant. [Francis Galton, 1875] The origins of developmental change Francis Galton (1875), the father of human and continuity of individual differences behavioral genetics, and by Thorndike were the focus of the first twin studies by (1905) and Merriman (1924). The question The MacArthur Longitudinal Twin Study is supported by the John D. and Catherine T. MacArthur Foundation through its Research Network on Early Childhood Transitions. Dr. Emde is supported by Research Scientist Award 5 K02 MH36808. We thank the families who contrib- uted their time and effort, as well as the many research assistants at the University of Colorado, Harvard University, Yale University, and The Pennsylvania State University who were involved in data collection, behavioral coding, data management, and analysis. Correspondence concern- ing this article should be