This happened to my great grandmother, I thought it was unusual, but I guess not. Came to the United States as a teenager not knowing English, but quickly pick

This happened to my great grandmother, I thought it was unusual, but I guess not. Came to the United States as a teenager not knowing English, but quickly picked it up. Eventually her french speaking elders all died off so she stopped speaking french out of circumstance, she never taught her kids french and french materials were not available at the time. In her 90s she said she didn't remember how to speak french. I thought it was sad but it actually didn't bother her because she didn't need to speak french anymore. Some people who didn't know her thought she was senile if she mentioned this to them.