Developing fluent and effortless reading is a major focus of educational training in the early school years and forms the foundation for the remainder of the curriculum. Given the importance of reading, we know surprisingly little about the interplay between genes and environment that influences reading development. Previous research has identified characteristics of childrens environment that are related to their reading ability. However, environmental differences between children are not independent of their genes. For instance, families with a strong genetic predisposition to dyslexia may have fewer books in the home because they do not enjoy reading. This concept is called gene-environment correlation (rGE) and is the focus of this proposal, leading to the following research questions: * What is the relative importance of genes and culture in transmitting reading ability from parent to child? If both mechanisms are of importance, this will induce rGE. * To which environmental exposures is reading ability linked? E.g. frequency of reading, or literacy practices at home? Is the association mediated by genetic or environmental factors and are environmental exposures themselves influenced by genotype? * Which genes account for the heritability of reading? I will tackle these questions by an advanced combination of methodologies: a longitudinal twin study, an extended twin-family study, and a gene-finding study. Phenotyping the required thousands of participants is feasible by using existing high-quality data and the development of a web-based reading test. The project bridges biological psychology, educational sciences, statistics, twin studies, and molecular genetics. The outcomes will generate insight in how to interpret previously established correlates of reading ability. Educational and clinical settings will benefit from the novel web-based reading test and from knowledge that can be implemented in reading-intervention programmes. Genetic research on reading in the Dutch language is currently lacking. This Veni will launch that field.