Why Do Identical Twins Have Different Fingerprints?

Identical twins don’t have identical fingerprints because of how fingerprints form. The whorls and ridges form during compressions of the skin on a foetus’s fingers, in a similar way to land masses buckling to form ridges under compression.

Not everything is alike about identical foetuses in the womb; their positions, the lengths of their umbilical cords, their movements, and their exposure to chance fluctuations in hormones will be different. These factors can all affect how the fingerprints of identical twins are formed, so although they may have similarities, they will always be slightly different.