A: their earwax

EARWAX MAY REVEAL CLUES ABOUT A PERSON’S IDENTITY AND HABITS: Forget the eyes, it’s your earwax that gives clues about you. A new study finds that you can glean information about a person’s ethnicity, foods they’ve eaten, and where they have been via the odors of their earwax. Researchers from Philadelphia conducted the study and say, “Earwax is a neglected body secretion whose potential as an information source has yet to be explored.” The researchers say they were inspired to study earwax after previous studies found you could learn a lot about a person’s identity via the smell of their underarm odor. (Fox)