Genes, environment, and dyslexia: the 2005 Norman Geschwind Memorial Lecture.

Olson, R. K. (2006). Genes, environment, and dyslexia: the 2005 Norman Geschwind Memorial Lecture. Annals of Dyslexia, 56(2), 205-238. https://doi.org/10.1007/s11881-006-0010-6

This article presents an overview of some methods and results from our continuing  studies of genetic and environmental influences on dyslexia, and on individual differences across the normal range that have been conducted over the past 25 years in the Colorado Learning Disabilities Research Center (CLDRC) and in related projects.  CLDRC investigators compare the similarities of identical twin pairs who share all  their genes and fraternal twins who share half their segregating genes to assess the  balance of genetic, shared family environment, and nonshared environment influences  on dyslexia and on individual differences across the normal range. We have learned  that among the children we have studied in Colorado, group deficits in reading  (dyslexia) and individual differences in reading across the normal range are primarily  due to genetic influences, and these genetic influences are often shared with some of  the same genetic influences on deficits and individual differences in language and  ADHD. We have also learned from our molecular-genetic linkage studies that there  are regions on several chromosomes likely to contain genes that influence dyslexia.  Several specific genes within these regions have been tentatively identified through  molecular-genetic association analyses, but much more research is needed to under 

stand the pathways among specific genes, regions of noncoding DNA that regulate  the activity of those genes, the brain, and dyslexia. I conclude with a discussion of our  research on individual differences in early reading development, on the role of early  learning constraints in dyslexia, and on how genetic influences are expressed through  their interaction and correlation with the environment.