Role of Heredity and Environment

About this chapter

Role of Heredity and Environment is the chapter on understanding children in an inclusive context. It answers a question every primary teacher faces — why do learners in the same class learn the same lesson so differently? It sets up two causes of individual differences: heredity, the inner biological factor, and environment, the outer surrounding factor. It begins with the biology of conception (zygote, 46 chromosomes — 23 from each parent, genes carrying 40-100 per chromosome), gives Peterson's, Douglas-Holland's and F.L. Ruch's definitions of heredity, then turns to environment using Anastasi's, Douglas-Holland's and Gilbert's definitions and Anastasi's mental-environment idea (library, laboratory, debate, museum). Arguments for heredity use twin-study correlations (identical twins 0.90, fraternal 0.70, siblings 0.50, parent-child 0.31, unrelated 0.30). Arguments for environment use Freeman's 71-children study (10-point IQ rise) and the James-Reace hill-vs-village twin study (19-point gap). The chapter closes with the Ross formula H X E X T = DL, Woodworth's 'both equally essential', Landis's 'capacities given, opportunities from environment', the seed-soil-yield analogy, and educational implications for the classroom teacher. CTET Paper 1 tests this through definition recall, twin-study correlations, the H X E X T formula, the seed-soil analogy, and pedagogy items on individual differences. The four tests — Practice 15, Quiz 15, Hard 15, Mastery 30 — cover all six topics at CTET depth.