ABSTRACT
When two people are learning a second language, what explains the differences in their ultimate level of second language proficiency? As with many individual differences, the explanation may be a combination of nature and nurture—genetics and environment, but the relationship between genetics and second language acquisition is currently understudied. This chapter provides an overview of the necessary background and theoretical perspectives relevant to this topic. Then the chapter reviews the extant research, which suggests that genetic differences related to dopamine may explain differences in language control, and also finds that dopamine-related genetic differences, in combination with language experience, may be related to bilingual proficiency in adulthood. Based on these initial findings, which lay the foundation for large-scale, genome-wide research on genetic differences in second language acquisition, the chapter proposes future directions for research on genetics and second language acquisition.
