I did state "native fluency" which is more descriptive. Anyway, sure, here's a source I found quickly which actually makes stronger claims than I did: https://

I did state "native fluency" which is more descriptive. Anyway, sure, here's a source I found quickly which actually makes stronger claims than I did: https://www.scientificamerican.com/article/at-what-age-does-our-ability-to-learn-a-new-language-like-a-native-speaker-disappear/ https://www.scientificamerican.com/article/at-what-age-does-...