Genetic and Environmental Influences on Literacy and Numeracy Performance in Australian School Children in Grades 3, 5, 7, and 9

Abstract

We examined the extent to which genes and the environment contributed to variation in and covariation among reading, spelling, grammar and punctuation, writing, and numeracy in Australian school children in Grades 3, 5, 7, and 9. Heritability was generally high: reading .58-.71 (excepting Grade 5 girls), spelling .68-.78; grammar and punctuation .52-.66, writing .39-.52, and numeracy .39-.79. Boys' performance varied more than girls in spelling and numeracy, and the common environment was a greater influence in girls than boys in Grade 3 numeracy and Grade 5 reading. Independent pathway models showed similar genetic and environmental structures at each grade with approximately one third to one half of the variation in each domain due to genes that influenced all domains. The covariation among the domains was largely mediated by genes. Results suggest substantial uniformity in the environmental factors influencing these academic domains.

Little Evidence That Socioeconomic Status Modifies Heritability of Literacy and Numeracy in Australia

“…Each year the National Assessment Program in Literacy and Numeracy (NAPLAN) tests are administered to students in Grades 3, 5, 7, and 9 in five academic domains: reading, spelling, grammar and punctuation, writing, and numeracy. As indicated earlier, genetic variation has been found to substantially contribute to variation in performance on the NAPLAN, whereas the influence of the shared environment was low to modest (Grasby et al, 2016). However, if a gene-SES interaction is present, then estimates from the standard twin model will be biased; specifically, estimates of genetic effects will be inflated (Purcell, 2002).…”

“…A major limitation in most studies of SES and academic achievement is the inability to distinguish the impact of SES on academic ability independent of innate influences on both. Genetic variation is a substantial contributor to individual differences in academic achievement; in developed countries, genes typically explain more than half of the variation in performance of these academic outcomes (de Zeeuw, de Geus, & Boomsma, ), and in Australia genetic influence on “high‐stakes” assessment of literacy, language, and numeracy in Grades 3–9 has been shown to range from around 50% to near 80% of variance (Grasby, Coventry, Byrne, Olson, & Medland, ).…”

The genetic and environmental effects on school grades in late childhood and adolescence

“…However, no differences were found between the heritability of arithmetic (a 2 = 68%; c 2 = 5%, e 2 = 27%) and language (a 2 = 67, c 2 = 10%, e 2 = 23%; [31]). Grasby et al did not only consider distinct domains of academic achievement but also included four age groups in an Australian sample [32]. Their results confirmed similarly-high influences of genetic effects on numeracy performance (61–79%) and language performance (39–78%) throughout all age groups included in the study.…”

Student achievement against national minimum standards for reading and numeracy in Years 3, 5, 7 and 9: A regression discontinuity analysis

“…Thirdly, studies of educational achievement in the general population have revealed a complex mix of child (including genetics), family, community and school influences on literacy and numeracy achievement (Marks 2006; Hattie 2009; Marks 2014) and the complex risk contexts of educational disadvantage (Brinkman et al 2013; Taylor et al 2019). Twin studies have consistently shown that reading achievement is highly heritable and stable across the school years (Grasby et al 2016; Rimfeld et al 2018). The results presented here are consistent with studies that have drawn attention to the stability of students’ academic achievement trajectories over time (Heckman 2008; Marks 2014; MacDonald & Carmichael 2018; Zubrick et al 2015; Cumming 2019).…”