The Germans who came to America mostly came from the northern parts. And various

—The Germans who came to America mostly came from the northern parts. And various studies indicate that just as Germany is a genetically diverse nation by European standards so there are significant IQ differentials by regions. Generally speaking, the south is cleverer than the north.”—Anatoly Karlin

In response to the question of why German Americans have a slightnly lower IQ than other groups.