I don't know about the "more grown up" (for lack of a better term!) when it comes to native languages. It reminds me of an argument that my younger sister and I had, concerning our "hometown!"
She says that where you graduate high school is your hometown; I feel that where I was born is my hometown. (Of course, we were both born in a town of about 2000 people, and moved to a "city" of about 100,000 people before we graduated high school.) So who's right, and who's wrong? I STILL feel like the town in which I was born is my hometown; she feels like Boise is her hometown.
Maybe it works two ways...especially since each of us have learned a second language since birth. (Just not the same second language...)
Just my mind going into "silly-overdrive!"