This seems unlikely. Ethnic groups are cultures, much more than associations of genes. African-Americans are ~80% West African ~20% British by ancestry but ther

This seems unlikely. Ethnic groups are cultures, much more than associations of genes. African-Americans are ~80% West African ~20% British by ancestry but there’s a lot more British in their culture than West African. Absent Indian jati style strict endogamy genetic distinctiveness will disappear quickly even with low levels of exogamy. Jatis in the same village have levels of genetic distance similar to Sweden-Sicily. Those are people whose last common ancestor was 1000-1500 years ago. There’s nothing like that anywhere in Europe. East Anglia is the English region with highest modern Germanic ancestry, 30%. Samples from graves from Anglo-Saxon invasions suggest almost 100% population replacement. That’s consistent with panmixia. As to red hair, attitudes change quickly. Kick a ginger day started with South Park.