International Longitudinal Twin Study

Twinboys sitting on a blanket reading books.

By testing the abilities of identical and fraternal twin pairs it is possible to estimate the genetic and environmental influence on culturally-based skills. This may provide a detailed picture of developmental starting points and trajectories.

This longitudinal twin study joins the expertise of Brian Byrne at the New England University, Australia on methods measuring individual differences in prereading and promoting this development with the behavioural-genetic expertise of the Colorado Learning Disabilities Research Center (CLDRC) with professor Richard Olson as the principal investigator. 

An international collaboration

In this project we include a large sample of identical and fraternal twin pairs from US, Australia, Norway and Sweden, beginning at preschool age 5, and continuing through their reading development in school to explore the genetic and environmental etiology of critical learning and attention skills in preschoolers, as well as genetic and environmental links between preschool behaviour and subsequent reading development.

The significance of the project is two-fold, theoretical and practical. Understanding how genes can influence the development of a culturally-based skill like reading is a special theoretical challenge. Written language is a recent, cultural addition to human thought and behaviour, and the relatively late appearance of writing in the human repertoire makes it unlikely that there is anything approximating a specific “reading gene” (or genes). Hence the heritability of the skill must rest on some basic processes which are shared with other mental functions. Our research will help solve this puzzle by providing further convergent evidence on the heritable, proximal causes of variation in reading skill.

Planning targeted interventions

The practical significance of the project lies in the identification of heritable processes which undermine literacy growth, the most important step in planning targeted interventions for children at risk because of their genetic backgrounds. This longitudinal twin study has the potential to provide a detailed picture of the developmental starting points and trajectories which are under the influence of genetic factors. The same information can inform the design of teaching materials in ways which complement heritable cognitive processes, with a view to achieving high levels of reading skill in the population as a whole.  


External researchers