Genetic and environmental influences on early literacy skills across school grade contexts

Abstract

Recent research suggests that the etiology of reading achievement can differ across environmental contexts. In the US, schools are commonly assigned grades (e.g., “A,” “B”) often interpreted to indicate school quality. This study explored differences in the etiology of early literacy skills for students based on these school grades. Participants included twins drawn from the Florida Twin Project on Reading (n=1313 pairs) aged 4 to 10 years during the 2006–2007 school year. Early literacy skills were assessed with DIBELS subtests: Oral Reading Fluency (ORF), Nonsense Word Fluency (NWF), Initial Sound Fluency (ISF), Letter Naming Fluency (LNF), and Phoneme Segmentation Fluency (PSF). School grade data was retrieved from the Florida Department of Education. Multi-group analyses were conducted separately for subsamples defined by “A” or “non-A” schools, controlling for school-level socioeconomic status. Results indicated significant etiological differences on pre-reading skills (ISF, LNF, and PSF), but not word-level reading skills (ORF and NWF). There was a consistent trend of greater environmental influences on pre-reading skills in non-A schools, arguably representing “poorer” environmental contexts than the A-schools. Importantly, this is the case outside of resources linked with school-level SES, indicating that something about the direct environment on pre-reading skills in the non-A-school context is more variable than for A-schools.

Longitudinal Associations Among Reading‐Related Skills and Reading Comprehension: A Twin Study

“…The exact sources of the shared environmental effects can only be surmised in the present study. However, according to previous research of environmental factors relating to reading achievement, they could include sources such as parental teaching (e.g., how often the parent tries to teach the child to read words and to print words in a typical week) (Sénéchal, Lefevre, Thomas, & Daley, 1998), parental influences toward creating environments of rich oral language (Burgess, Hecht, & Lonigan, 2002), chaotic home environment (Taylor & Hart, 2014), shared book reading by a teacher and a child (Piasta, Justice, McGinty, & Kaderavek, 2012), school quality (Haughbrook, Hart, Schatschneider, & Taylor, 2016), and/or school-level SES (Hart, Soden, Johnson, Schatschneider, & Taylor, 2013).…”

Annual Research Review: Reading disorders revisited – the critical importance of oral language

“…A small number of studies have attempted to answer this question using genetically sensitive designs, but findings are inconsistent. Haughbrook, Hart, Schatschneider, and Taylor (2017) compared the etiology of reading skills in twins attending schools that varied in quality, comparing ‘A’ schools (in which the progress of pupils is generally better) versus ‘non‐A’ schools (with lower pupil attainments). Shared environmental influences between twins were larger in ‘non‐A’ than ‘A schools’, and conversely, there were greater genetic influences on the reading of those attending ‘A’ schools.…”

The Academic Development Study of Australian Twins (ADSAT): Research Aims and Design

“…While heritability of literacy and numeracy is consistently moderate to high across studies, the estimates vary across different samples, as do the portions of variance attributed to shared and nonshared environment (Little et al, 2017). For example, while reports of the Twins Early Development Study conducted in the UK since 1996 usually emphasize high heritability of educational achievement alongside large nonshared environment estimates and negligible shared environment (e.g., Harlaar et al, 2007Harlaar et al, , 2010Harlaar et al, , 2013, other studies in the USA reveal lower heritability estimates and nonshared environment alongside higher shared environment estimates (Haughbrook et al, 2017;Logan et al, 2013). The differences in results from samples in two countries highlight that heritability estimates and environmental influences may be context-or study-dependent (Daucourt et al, 2020;Haughbrook et al, 2017;Little et al, 2017), and that behavior genetic studies of educational outcomes conducted in different environments are warranted.…”