While 23andMe’s Ancestry Composition can tell you where in the world your ancestors came from, it cannot yet tell you who you should root for in the World Cup match between France and Germany.
23andMe’s analysis of DNA uses reference populations to figure out where your ancestors lived back over 500 years ago, before the age of migration. But for some populations that shared genetic history, like the French and Germans, accurately making that distinction is, so far at least, problematic. Ancestry Composition cannot yet distinguish between your French and German ancestry. That means that some customers get results that lump their French and German ancestry together.
But just as the teams themselves are mixed with players not just from Europe but from Algeria, Turkey and West Africa, their fans too come from all over the world. The differences between “Les Bleus” and “Die Mannschaft” are more on the field than they are in the players or their fans DNA.