Iris
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.)