A twin study of reading in Chinese children learning English as a second language

Abstract

A fundamental issue for reading research concerns the heredity of language and reading acquisition. Despite the emerging behavioral genetics research on English as a first language, the roles of heredity and environment in learning English as a second language remain unknown. This study extends past research by employing a twin study design to examine the relative contributions of genetic and environmental effects on Chinese children learning English as a second language. We tested 150 pairs of monozygotic (MZ) and 150 pairs of same-sex dizygotic (DZ) twins aged from 4 to 11. We assessed children's word decoding skills, vocabulary knowledge, phonological awareness, orthographic skills, naming speed with a battery of tasks in English and we also measured children's nonverbal IQ. Zygosity was estimated by parent and confirmed with saliva swab. In addition, we asked the parents to complete a demographic and home literacy questionnaire. A series of univariate statistics will be computed and the data will be fitted in the framework of the ACE model to identify the variances of genetic, common environmental, unique environmental factors and gene x environmental interaction controlling for age effect. Based on the results, we will discuss how much genes account for the individual variations in learning to read in a second language and whether an affluent environment can foster the growth of reading abilities in a second language. Fossilization (the phenomenon of which learners of second language are constrained with the cognitive limitations on acquiring a language as native-like) will also be discussed.