Nicholas Wade’s credible new book challenges conventional wisdom about genetics.
There is nothing new there in the age-old nature-nurture game. Does it really need saying that people who are more closely related likely have more traits in common? "Race" and "ethnicity" are just words for common ancestry, like "distant cousins." Early humans spread around the earth, and bred with others in their own neighborhoods just like Darwin's finches. Naturally, differences happened but not to the extent of new species, but enough so that people recognize their cousins.