What do we know about individuals who reach near-native levels in speaking another language? Social environment!
Achieving Native-Like Second Language Proficiency (Speaking) by Betty Lou Leaver is a research-based catalogue of factors that would seem to predict ability to reach the highest level of foreign language proficiency and is based on common characteristics shared by more than 200 near-native speakers, identified by self-report, survey, and interviews by master testers. One of those common characteristics turned out to be the social environment in childhood. Nearly all survey respondents reported growing up in a bilingual or multilingual home or community. The conjecture is that having been surrounded by other languages, (1) additional sounds (not present in the native language) lodged in the brain for later use (whereas, typically, unused sounds disappear around age 15 or even earlier) and (2) the concept of another language as a form of communication facilitated the embrace of any other language later not as a system of words and grammar rules to be learned but rather as a tool f...