Genetic?? and Environmental Influences on the Development of Reading and Related Cognitive Skills
Everyone would agree that there are environmental influences on reading development, consistent with the “environmental” part of my title, but the “genetic” part of the title may raise a few questions and eyebrows. Indeed, there are large cultural differences in levels of literacy both between and within countries that have no relation to genetic differences (D.R. Olson, 2002). However, even within relatively homogenous cultural environments that are strongly supportive of reading development, some children fall far behind their peers. These children may or may not be labeled as “dyslexic,” but their most salient characteristic is a reading level that is well below the norm, typically below the local 10th percentile in most research studies. Our research on English reading development in the United States has focused on the average genetic and environmental contributions to membership in this low-reading group without obvious cultural (impoverished schools, English as a second language) or overt biological (i.e., brain damage) constraints on their reading development.