My family is part German. I had a great uncle who was killed when his boat carrying supplies to Russia from the U.S. was sunk by a German U-Boat.
You are confused. Ethnicity or ancestry has much less of a tie on someone’s loyalties than their religion. Islam is a religion, a belief system, independent of someone’s genetics and ancestry. Look at the wannabe white terrorists who have taken Muslim names as an example of the flaw in your rant.