There are two distinct genetically determined types of earwax (cerumen). The wet type, which is dominant, and the dry type, which is recessive. Asians and Native Americans are more likely to have the dry type of earwax (gray and flaky), while white and black people are tend to have the wet type (light to dark brown and moist).
The difference in earwax type has been tracked to a single base change in a gene known as “ATP-binding cassette C11 gene.” In addition to affecting earwax type, this difference also reduces sweat production. Researchers speculate that the reduction in sweat was beneficial to the ancestors of East Asians and Native Americans who are thought to have lived in cold climates.