I don't believe that in Lower Silesia only 21% of Germans had R1a.
In my old sample from 2016 it was over 40% R1a for Lower Silesia:
https://www.eupedia.com/forum/threads/y-...ww2.32293/
My sample size was also bigger because 50 persons from Lower Silesia and 50 from Upper Silesia (in total 100 from Silesia).
In this German Project there are only 30 people from Lower Silesia.
In my old sample from 2016 it was over 40% R1a for Lower Silesia:
https://www.eupedia.com/forum/threads/y-...ww2.32293/
My sample size was also bigger because 50 persons from Lower Silesia and 50 from Upper Silesia (in total 100 from Silesia).
In this German Project there are only 30 people from Lower Silesia.