My mother is Norwegian and my father is German. I grew up in Germany. When we were young my mother would speak Norwegian with us. But she stopped when we had friends over because it seemed rude to her. Eventually she stopped entirely.
I wish I had kept it up. Although apparently it wouldn't have done us much good in most of Norway. When my father had some Norwegian business partners over he wanted to impress them with his Norwegian. They didn't understand a word because he learned it from my mother who apparently has a very thick accent.