Are fingerprints different between identical twins?

Answer

Fingerprints form in the womb partly by chance, so identical twins with the same DNA still have different prints.

Context

Fingerprint ridges begin forming in the fetus during roughly the first half of pregnancy, and the overall pattern (loop, whorl or arch) is set by about the middle of gestation. Genes influence the general pattern type, which is why twins and relatives often share broad similarities, such as both having whorls. The fine detail, however, depends on the conditions in the womb.

Researchers point to factors such as the pressure and shape of the growing finger pad, the position of the fetus, the flow of amniotic fluid and the timing of ridge growth. Each finger experiences slightly different conditions, so even the ten fingers of one person differ, and identical twins, who share nearly all their DNA, do not end up with matching prints. Their prints may look alike in overall type, which can trick casual observers, but the small ridge details used in forensic comparison, called minutiae, differ.

This is why fingerprint systems can in principle tell twins apart even though DNA profiles usually cannot, since standard DNA tests generally match for identical twins. Fingerprint evidence still has limits: partial or smudged prints from crime scenes can lead to errors, and scientific reviews have urged careful validation of examiner methods instead of claims of absolute certainty.