We investigated the stability and developmental interplay of word reading and spelling in samples of Swedish (N = 191) and U.S. children (N = 489) followed across four time points: end of kindergarten, grades 1, 2, and 4. Cross-lagged path models revealed that reading and spelling showed moderate to strong autoregressive effects, with reading…

Modern behavior-genetic studies of twins in the United States, Australia, Scandinavia, and the United Kingdom show that genes account for most of the variance in children's reading ability by the end of the 1st year of formal reading instruction. Strong genetic influence continues across the grades, though the relevant genes vary for reading words…

Using nationally representative data from the Longitudinal Study of Australian Children (LSAC; N = 5,107), this study assessed prospective connections between children's early education and care (EEC) experiences from infancy through preschool and their cognitive and behavioral functioning in 1st grade. Incorporating 6 waves of data, analyses…

Grade 1 literacy skills of twin children in Australia (New South Wales) and the United States (Colorado) were explored in a genetically sensitive design (N = 319 pairs). Analyses indicated strong genetic influence on word and nonword identification, reading comprehension, and spelling. Rapid naming showed more modest, though reliable, genetic…