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Associations Between Reading Achievement and Independent Reading in Early Elementary School: A Genetically Informative Cross-Lagged Study


  • We gratefully acknowledge the ongoing contribution of the parents and children in the Western Research Reading Project (WRRP). We thank Philip S. Dale for his comments on an earlier draft of this manuscript. WRRP is supported by NICHD Grant HD38075 and NICHD Grant HD059215.

concerning this article should be addressed to Nicole Harlaar, University of Colorado at Boulder, Muenzinger D244, 345 UCB, Boulder, CO 80309-0345. Electronic mail may be sent to


This study used a cross-lagged twin design to examine reading achievement and independent reading from 10 to 11 years (= 436 twin pairs). Reading achievement at age 10 significantly predicted independent reading at age 11. The alternative path, from independent reading at age 10 to reading achievement at age 11, was not significant. Individual differences in reading achievement and independent reading at both ages were primarily due to genetic influences. Furthermore, individual differences in independent reading at age 11 partly reflected genetic influences on reading achievement at age 10. These findings suggest that genetic influences that contribute to individual differences in children’s reading abilities also influence the extent to which children actively seek out and create opportunities to read.