Eyes are the window to your soul and your identity. The iris, a muscle that opens and closes the pupil to control how much light enters the eye, has tiny textural patterns. DNA determines the color and structure of the iris, but its random pits, furrows, swirls, and rifts occur during fetal development, which makes every iris unique (even your two irises don’t match each other). The patterns are thought to appear as the fetus opens and closes its developing eyes, and iris tissues tighten and fold. (Make sure you never touch your eyes or any of these seven body parts.)
Trace the rim of your ear: Feel those curves and ridges? You’re the only person in the world with that exact shape. In one British study, researchers developed an algorithm that could identify a single individual out of more than 250 others with a 99.6 percent accuracy rate by analyzing how light reflects off the curves of the ears. The ear is such a handy identifier that Yahoo is developing technology to unlock smartphones with an ear scanner. Someone receiving a call would unlock the phone by simply pressing it to the ear.