Many years ago when my daughter was two, I found that we had communication problems. One day, she told me a lie. I told her that she was lying. She turned to me and loudly roared. Confused, I repeated that she was lying. Again, she roared at me. It took several minutes for me to realize that I she thought I was calling her a "lion" because I wasn't pronouncing the word properly. I think that was the day that I decided to move away from the south back to the land of speaking properly. Two years later I left Florida and moved back to New York.
I had no idea what seven years of living in the south with a man from Alabama had done to my speech patterns until I moved back. I had people stare whenever I said I was "fixin'" to do something. I remember when I first moved there that I would tease other people about using the word "fixin'". Somewhere over time, it entered my vernacular and stuck and I didn't realize it until I was back in the land of proper speech.
My daughter was four when we moved back to New York and I was amazed how quickly her southern draw disappeared and her vernacular changed to northern expressions. I think it may have been because every time she said "yes ma'am" or "no, sir" people's heads turned and some people even laughed at her. She learned quickly that she was supposed to just say "yeh" or "nah".