My Grandparents were Germans that came to live in Chicago after WW2.
The both learned English, but never gave up their culture, way of thinking or eating habits. Nothing cahnged them. They were german through and through. I remember my Grandpa at age 75 telling me that he had just noticed that his thoughts were starting to be in English rather than German. Despite that, he never changed into a 100% American. Not even close!