Heritage speakers who re-learn their childhood language in adulthood are an important group for the study of L3 acquisition. Such re-learners have selective advantages over other L2/L3 learners in phonetics/phonology, but lack a global advantage at re-learning the prestige variety of their L1. These learners show asymmetrical transfer effects in morphosyntax: transfer occurs only from the dominant language. Two tentative explanations for this asymmetry are suggested. First, re-learners may deploy the skills acquired in a classroom setting, where they have used only their dominant language. Second, re-learners may implicitly strive to increase the typological distance between their childhood language and the language of classroom instruction. These findings have implications for models of L3/Ln learning: the Cumulative Enhancement Model, the Typological Proximity Model, and the L2 Status Factor Model. The data discussed in this paper are most consistent with the latter model, but they also highlight the significance of the typological distance between languages under acquisition.