Do identical twins have the same fingerprints?

 A lot of people wonder about this. The answer is “No”.  Our DNA contains the instructions for making us who we are. Identical twins have DNA that is almost indistinguishable, that is, identical.  Identical twins form when a single fertilized egg splits into two after conception. They have the same genetic makeup (genotype). But there are subtle differences. Enough differences that people, especially parents, can tell them apart.

Fingerprints are not the result of genetics alone. Fingerprints, along with such characteristics as height, weight, body form, reflexes, metabolism, and behavior are determined by a person’s individual genes and by the interaction with nature (phenotype).

It’s that age old “nature vs. nurture” question. How much of what we are as humans is the result of our genetic make-up (nature) and how much is determined by our interaction with the environment (nurture).

By environment, we’re talking about how you’re raised, your home situation, what you eat, how you sleep, your siblings, and the air you breathe. In short, everything and everyone around you.

Here’s where it gets really interesting. Fingerprints are one of those traits that are the result of development of the baby during pregnancy. Those factors include blood pressure, nutrition, position in the womb, and growth rate by the end of the first trimester.

The creation of the patterns of the fingerprint are caused by stresses in a sandwiched sheet of skin called the basal layer. The basal layer grows faster than surrounding layers.  This basal layer buckles and folds in several directions, forming complex shapes. It’s a very random process.

The fingerprints of both identical twins are quite similar, but there are differences in the pattern of arches, whorls, and loops. These differences are caused by the random stresses in the womb. Even the length of the umbilical cord has an influence. There’s also differences between the fingers on any individual’s hand.

Probably the most celebrated case were the Dionne quintuplets born in Ontario, Canada in 1934. The five identical (same DNA) girls all had different fingerprints and handprints.

Fingerprint and handprints are now being used by security people to correctly identify persons. It is said to be as accurate as a retinal scan.

It is worth adding that fraternal twins develop from two different eggs. Fraternal twins are no more closely related than ordinary siblings. They just happen to share the same growing space for nine months.




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