The impact of L1 and L2 on the use of relative clauses in L3 English

Abstract This study examines the use of English relative clauses (RCs) in third language (L3) learners by analyzing 144 argumentative essays written by native speakers of Persian (L2 English learners) and native speakers of Azerbaijani and Sorani Kurdish (L3 English learners, with Persian as their L2). We investigated how learners’ first (L1) and second (L2) languages influence L3 RC formation, focusing on typological and structural relationships among the languages. Results revealed that L2 Persian facilitated L3 RC acquisition, but its effect depended on L1 background: L1 Azerbaijani speakers, whose L1 is typologically more distant from Persian, outperformed L1 Sorani Kurdish speakers, indicating that greater L1-L2 distance enhances L2 transfer. Structural proximity between L2 and L3 further promoted accurate RC production, and specific syntactic properties of RCs in L2 were transferred to L3, improving both accuracy and variety. These findings underscore the complex interplay of crosslinguistic influences in multilingual acquisition and highlight the role of L1-L2 typology and L2 structural experience in shaping L3 development.