Learning a foreign language changes one's brain so much that it's not surprising to see many articles espousing its benefits for keeping one's brain sharp as one ages. However, one doesn't necessarily think about what learning another language does to one's personality, nor is that written about often. Despite that, this has been on my mind in the last year and a recent meeting with a friend really highlighted it. I do believe that the way we express ourselves, and maybe even our personality itself, changes when we speak a different language.
My friend, whom we'll call N, has been practicing English with me for almost half a year now. Thanks to a lot of dedicated study on her own, she has really come along far to improve her already-quite-decent English. Now she's to the point that we are discussing picky grammar constructions that many native speakers get wrong.
I hadn't been speaking that much German with her during earlier meetings, but she has been good about pushing me lately to communicate more in German. N shared her realization that when I speak German, I am like a different person. She knows me in the context of my English speaking so she has an impression of who I am, but in German, the impression would be different if we weren't already acquainted. (I would be amused if it were something to the effect of "woo, is she dumb! She speaks like a baby," but N is too nice to say something like that.)
From there, N realized that she doesn't present herself the same way in English as she does in German. She thought that I wasn't initially meeting the "real" her but as her language is progressing, she's expressing herself better in English and is closer to her true self.
That raises a good question: do people feel different about themselves when they speak different languages? Is it a result of not having a firm footing in the new language? Do they act differently? Does language define us?