Response to early literacy instruction in the United States, Australia, and Scandinavia: A Behavioral-Genetic analysis.

The purpose of this study is to examine how genetic and environmental factors affect the early reading and writing skills of twins in a pre-school class until the end of the first year of primary school. The US, Australia and the Scandinavian countries are compared with a view to identifying possible differences between the countries in reading and writing skills.

The results are presented in the form of comments on statistical analyses. The statistical results
indicate that patterns of genetic and environmental influences vary depending on educational context. However, individual differences are increasingly explained by genetics when the intensity of the early education is increased. The longitudinal analyses show continuity in the genetics between pre-school classes and the first year of primary school across countries as regards both reading and writing.

The study is a cohort study. Questionnaires were completed by all twins born in the participating countries. A database consisting of the twins' individual data is used in the data collection.  The database is updated regularly as new parents of twins are invited to submit data on their newborn twins to the database.

Samuelsson, S.; Byrne, B.; Olson, R.K.; Hulslander, J.; Wadsworth, S.; Corley, R.; Willcutt, E.G.; DeFries, J. C. (2008). Response to early literacy instruction in the United States, Australia, and Scandinavia: A Behavioral-Genetic analysis: Learning and Individual Differences 18 (3) S. 289-295.