Identical Twins Don’t Have Identical Fingerprints, Even from Birth

Today I found out that no two people in this world have identical fingerprints, not even identical twins. You would expect identical twins to have the same fingerprints as they are monozygotic, which means that they develop when a single fertilized egg splits in two, leading to two embryos. As they both came from the combination of the same egg and sperm, these twins have virtually indistinguishable DNA.

So why aren’t their fingerprints identical from birth? Fingerprints are not entirely a genetic characteristic. They are a part of a ‘phenotype’ which means they are determined by the interaction of an individual’s genes and the intrauterine environment (differing hormonal levels, nutrition, blood pressure, position in the womb and the growth rate of the fingers at the end of the first trimester).

Minor differences in fingerprints arise from random local events during fetal development. The genes determine the general characteristics of the patterns of fingerprints. However, inside the uterus, finger tissue comes in contact with the amniotic fluid, other parts of the fetus and the uterus. Some experts point out, for example, that touching amniotic fluid during weeks 6-13 of pregnancy significantly changes the patterns of fetus’s fingerprints. Overall, identical twins’  fingerprints tend to be similar, but there always will be subtle differences making even their fingerprints unique.