David Goldenberg of MinuteEarth explains how fingerprints are formed. These singular identifiers first start out as volar pads that form in utero. These pads soon give way to the ensuing chaos of development, which causes each pad to form a unique pattern of ridges, whorls and arches that are unlike anyone else’s.
Because of the chaotic way fingerprints develop and the multiplying effect of compound probability, it’s basically impossible for any two fingers to have matching prints.
