Genetic and environmental influences on learning Chinese language and literacy skills

This thesis investigated the etiology of individual differences in Chinese language and literacy skills with a two-wave longitudinal design using a sample of 312 Chinese twin pairs aged 3 to 11 in Hong Kong. Children were individually given tasks of Chinese word reading, receptive vocabulary, phonological memory, tone awareness, syllable and rhyme awareness, rapid automatized naming, morphological awareness, and orthographic skills, as well as nonverbal reasoning and audiometric screening tests. They were tested again on the same tasks, except nonverbal reasoning, one year after the initial testing. Children’s saliva was collected to perform SNP testing for zygosity determination. Also, their demographic information, home literacy environment profile, and motivation for learning text, were obtained from parent-rated questionnaires. Overall, there were four major findings on Chinese language and literacy abilities with the effects of age and nonverbal reasoning controlled for. First, genes and environments had differential influences on various skills, and there was a possibility of different etiology in language and reading development. Second, socioeconomic status and home literacy environment were plausible mediators but not moderators of general language and reading abilities. Third, the stability of various skills across a one-year time period was mainly mediated by genetic influences, but shared environmental factors also influenced syllable and rhyme awareness. Also, new genetic and environmental factors came into play at Time 2 for word reading, and results suggested new genetic influences and new shared environmental influences emerged at Time 2 for tone awareness and morphological awareness respectively. Fourth, both genes and environments contributed to parent-rated communicative ability and motivation for learning text. Furthermore, the link between word reading and parent-rated motivation was mediated by genetic processes. The universality of the genetic and environmental origins across languages and their specificity to Chinese, as well as the implications of these findings, were discussed.EThOS - Electronic Theses Online ServiceGBUnited Kingdo