Genetic variation and individual differences in language

Drawing upon recent conceptual and analytical trends in molecular genetics, this chapter explores how molecular genetics might be used to elucidate language differences in normally developing individuals, including variation in linguistic generalization skills. We propose an endophenotype approach, complemented with learning-based tasks and process measures, as a step forward in studying variation in the underlying brain mechanisms that support normal language learning and processing. We discuss how well-formulated and theoretically grounded endophenotypes may offer greater conceptual clarity, objectivity, and precision over many conventional assessments used in language genetics. This framework aims to uncover the biological part of an emergentist account to language, and provides a complement to investigations into more experientially based factors. Keywords: Endophenotype; genetic variation; individual differences