Added value measures in education show genetic as well as environmental influence

Abstract

Does achievement independent of ability or previous attainment provide a purer measure of the added value of school? In a study of 4000 pairs of 12-year-old twins in the UK, we measured achievement with year-long teacher assessments as well as tests. Raw achievement shows moderate heritability (about 50%) and modest shared environmental influences (25%). Unexpectedly, we show that for indices of the added value of school, genetic influences remain moderate (around 50%), and the shared (school) environment is less important (about 12%). The pervasiveness of genetic influence in how and how much children learn is compatible with an active view of learning in which children create their own educational experiences in part on the basis of their genetic propensities.

Figure 1. Bivariate analysis of g and achievement.

Panel A = g and teacher-rated achievement at 12 years. Panel B = g and test achievement at 12 years. g =  general cognitive ability; Ach-Tch  =  Teacher-rated achievement; Ach-Test  =  test achievement; A =  additive genetic; C =  Shared environment; E =  Non-shared environment. The figures represent the results from a standardized Cholesky decomposition of twin data. 95% confidence intervals of the path estimates are shown in parentheses. The first factors assess genetic (A₁), shared (C₁) and non-shared environmental (E₁) influences on g, some of which may also influence school achievement. The second factor estimates influences on achievement that are independent of the influences on g (A₂, C₂ and E₂). Results indicate significant residual genetic influence on school achievement, even when the genetic and environmental co-variance with general cognitive ability has been removed (see the A₂ path estimate).

Figure 2. Bivariate analysis of 10 and 12-year achievement.

Panel A =  Teacher-rated achievement at 10 and 12 years. Panel B =  Test achievement at 10 and 12 years. Ach-Tch  =  Teacher-rated achievement; Ach-Test  =  test achievement; A =  additive genetic; C =  Shared environment; E =  Non-shared environment. The figures represent the results from a standardized Cholesky decomposition of twin data. 95% confidence intervals of the path estimates are shown in parentheses. The first factors assess genetic (A₁), shared (C₁) and non-shared environmental (E₁) influences on 10-year achievement, some of which may also influence 12- year school achievement. The second factor estimates influences on 12-year achievement that are independent of the influences on 10-year achievement (A₂, C₂ and E₂). Results indicate significant residual genetic influence on 12-year school achievement, even when the genetic and environmental co-variance with previous achievement has been removed (see the A₂ path estimate).

Figure 3. Trivariate analysis of 10-year achievement, general cognitive ability and 12-year achievement.

Panel A =  Teacher-rated achievement. Panel B =  Test achievement. g =  general cognitive ability; Ach-Tch  =  Teacher-rated achievement; Ach-Test  =  test achievement; A =  additive genetic; C =  Shared environment; E =  Non-shared environment. The figures represent the results from a standardized Cholesky decomposition of twin data. 95% confidence intervals of the path estimates are shown in parentheses. The first factors assess genetic (A₁), shared (C₁) and non-shared environmental (E₁) influences on 10-year achievement, some of which may also influence g and 12-year achievement. The second factor estimates influences on 12-year g that are independent of the influences on 10-year achievement, and which may also influence 12-year achievement (A₂, C₂ and E₂). The third factor (A₃, C₃ and E₃) estimates influences on 12-year achievement that are independent of those on 10-year achievement and 12-year g. Results indicate significant residual genetic influence on school achievement, even when the genetic and environmental co-variance with previous achievement and general cognitive ability has been removed (see the A₃ path estimates).