But as an embryo develops, the print is affected by the growth of the fingertips and the creation of blood vessels, nerves and connective tissue. Tiny details are formed haphazardly in the skin folds, which means that not even monozygotic twins have the same fingerprints. Once the fingerprint has been formed, it will never change. If the skin on a finger is lost, the fingerprint will temporarily disappear, but when the skin regenerates, the fingerprint will be exactly the same as it was.

In rare cases, all fingerprints may change or disappear. Some types of chemotherapy will make the skin of the fingertips swell, making fingerprints disappear. In most cases, they return later on, but in a few patients, they disappear for good.