So I had a long running debate with one of my now deceased uncles...

The debate was over whether these ancestors should be considered French or German. I had a work friend from Germany, so I asked him, he looked at me quizzically and said: "What language did they speak? If you live in Germany but speak French, you are French. If you live in France and speak German, you are German.". I laughed and said I have no idea what language they spoke.