Life's Little Mysteries

Do identical twins have identical fingerprints?

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Not quite.

Despite looking exactly alike, identical twins do not have identical fingerprints. (Image credit: Shutterstock)

Your fingerprints are different from those of everyone else on Earth. The whorls and ridges on your fingertips are determined partly by your genetic makeup. But if you had an identical twin with the same genetic makeup as you, would your fingerprints still be unique? 

Identical twins, also known as monozygotic twins, come from a single embryo that divides in two early on in development. The result is two individuals that share almost the same genetic information from each parent and look almost exactly the same. Identical twins are essentially clones of one another, although genetic mutations in the womb mean they don't quite share 100% of the same DNA, Live Science previously reported.

However, despite having almost-identical DNA, monozygotic twins don't have identical fingerprints. 

Related: Why do we have fingerprints? 

"Whilst identical twins share more similarities than two random individuals, their fingerprints are different enough that they can be used to uniquely identify them," Simona Francese, a forensic scientist and expert on fingerprints at Sheffield Hallam University in the U.K. , told Live Science.

No one on Earth has the same fingerprints.

"The probability of two individuals sharing the same fingerprints is 1 in 64 billion," Francese said. "To this day, no two fingerprints have been found to be identical."

Fingerprints are also different on each finger. "Every digit has a different ridge pattern, which produces a different fingerprint," Francese said.

But if identical twins share almost exactly the same DNA, why aren't their fingerprints indistinguishable from one another?

It turns out that DNA isn't the only factor that influences a person's fingerprints, even though it does play a major role in determining the ridge pattern characteristics, Francese said. "Different environmental factors in the womb also play a role in the development of fingerprints." 

Fingerprints are formed between 13 and 19 weeks of fetal development. The fetal position in the womb, access to nutrients and even the length of the umbilical cord can all affect fingerprints, Francese said. 

After twins are born, other factors can also change fingerprints. "Skin conditions, scars, burns and, in certain rare cases, medications can permanently or temporarily alter the ridge details," Francese said.

So, while identical twins might be able to fool their friends and family about who's who, there is always one surefire way to tell them apart.

Originally published on Live Science.

Harry Baker
Harry Baker
Senior Staff Writer

Harry is a U.K.-based senior staff writer at Live Science. He studied marine biology at the University of Exeter before training to become a journalist. He covers a wide range of topics including space exploration, planetary science, space weather, climate change, animal behavior and paleontology. His recent work on the solar maximum won "best space submission" at the 2024 Aerospace Media Awards and was shortlisted in the "top scoop" category at the NCTJ Awards for Excellence in 2023. He also writes Live Science's weekly Earth from space series.