Predicting literacy at age 7 from preliteracy at age 4.

Early literacy experience and preliteracy knowledge have been shown to predict later literacy outcomes. Using a representative sample of 3,052 same-sex twin pairs (6,104 children) in the United Kingdom, we explored phenotypic and etiological interrelationships among early literacy experience, preliteracy knowledge, and school-based literacy outcomes (reading and writing). Both literacy experience and preliteracy knowledge at age 4 significantly and independently predicted literacy at age 7. Both measures also showed genetic influence that significantly predicted literacy at age 7, although genetic mediation was stronger for preliteracy knowledge than for early literacy experience. However, for both measures, shared environmental factors explained most of the association with literacy at age 7.