Those DNA kits work differently than what you might expect. When they say “you’re 20% German”, what they mean is that you’ve got 20% of the genetic markers they’ve identified in modern people who identify as German.

This might not seem like a big difference, but it is because genetics doesn’t respect political boundaries. Ancestry will not tell you that you’re 60% Texan because “Texas” isn’t a recognized biological origin. Even though people have been there as long as they’ve been in Mexico.

You also have to accept that 20th Century Germans who’ve participated in DNA testing is the absolute standard for what a “German” is.

Nonsense. The idea of “national DNA” is incoherent leftovers from race-theory.