The purpose of this study was to test the directionality of influence between reading comprehension (RC) and print exposure (PE), thereby estimating genetic and environmental effects of this relation. The sample consisted of 910 twins in fourth through ninth grades (M[subscript age] = 12.33 years, SD = 1.41) from the Florida Twin Project on…

This study explores the co-development of two related but separate reading skills, reading fluency and reading comprehension, across Grades 1-4. A bivariate biometric dual change score model was applied to longitudinal data collected from 1,784 twin pairs between the ages of 6 and 10 years. Grade 1 skills were influenced by highly overlapping…

The development of reading skills in typical students is commonly described as a rapid growth across early grades of active reading education, with a slowing down of growth as active instruction tapers. This study examined the extent to which genetics and environments influence these growth rates. Participants were 371 twin pairs, aged…