People of African and European ancestry have predominantly wet earwax. Asians, Inuit and Native North Americans have predominantly dry earwax, as they have a gene that prevents cerumen from mixing with their earwax.
Researchers identified a gene that alters the shape of a channel that controls the flow of molecules that directly affect earwax type. They found that many East Asians have a mutation in this gene that prevents cerumen, the molecule that makes earwax wet, from entering the mix.
Scientists believe that the mutation reached high frequencies in Northeast Eurasia and, following a population increase, expanded over the rest of the continent. Today distribution of the gene is highest in North China and Korea