Contributions of genetic, home and school environmental factors to language learning among Chinese-English bilingual children

Abstract

Research has shown that language and reading abilities are highly heritable. Do genetic, home and school environmental factors make different contributions to first (L1) and second language (L2) learning? A study with 370 pairs Chinese-English bilingual twins was conducted to address this question. The children were administered seven measures on language and reading and their parents were given a questionnaire on information of SES, home and school factors. Results of multiple regression show that SES, home Cantonese/ English speaking, school tier, and medium of instruction are significant predictors of L1 and/or L2 abilities. These identified environmental factors were examined in genetic mediation models together with the genetic (A), shared environmental (C) and nonshared environmental (E) factors. It was found that genetic factors explained 53%, SES and home language explained 11% and school factors explained 2% of variance in L1 Chinese abilities. For L2 English learning, genetic factors only accounted for 22% of variance. 44%, 17% and 11% were explained by shared environment, home and school factors respectively. The present findings suggest that learning a native and a second language is influenced by different genetic and environmental factors. Since most children learn their mother tongue from birth at home, both genetic and home factors (like home resources and language environment) are crucial for L1 learning. When children learn a second language, normally later from school, school factors like resources, support, and medium of instruction appear to show significant contribution. These findings have educational implications for supporting bilingual language learning.