Fingerprints are one of the most unique characteristics of human beings. No two people, even identical twins who share the same DNA, are believed to have identical fingerprints.
What Makes Fingerprints Unique?
Fingerprints are formed during fetal development in the womb. They begin to form around the 10th week of gestation and continue to become more defined until around the 24th week. Fingerprints form from the microscopic ridges and furrows on the pads of the fingers and thumbs. It is believed that these ridges and furrows form somewhat randomly as the skin on the fingers grows and folds in the womb.
The exact patterns, loops, whorls and arches that make up a fingerprint are determined by these ridges and furrows. Even the slightest difference in the growth and folding of this skin will result in different fingerprints. While identical twins share the same DNA, their fingerprints develop independently in the womb. Slight variation in their fetal environment and development means their fingerprints will differ.
Uniqueness of Fingerprints
No two fingerprints have ever been found to be exactly alike, even when analyzing the fingerprints of identical twins. Fingerprints are so unique that they have become accepted as a reliable means of identification in criminal investigations and security systems. The chance of two people having identical fingerprints is estimated to be 1 in 64 billion.
Fingerprints are made up of various patterns including arches, loops, whorls and combinations of these. There are three basic fingerprint patterns:
- Arches – fingerprint ridges enter from one side, rise in the center and exit the other side
- Loops – fingerprint ridges enter from one side, form a curve and exit the same side
- Whorls – fingerprint ridges form circular or spiral patterns
The way these patterns are formed comes down to fine details in the ridges and furrows that are nearly impossible to be identical from person to person. Even the fingerprints of identical twins, who share the same DNA, will differ in these microfeatures that give rise to unique patterns.
Why Identical Twins Have Different Fingerprints
While identical twins derive from the same fertilized egg, split into two embryos, their development and fetal environment will have slight variations that impact fingerprint formation:
- Slight difference in amniotic sac environment – Identical twins do not share the exact same space and conditions in the womb. Slight variations in their fetal development environments will cause differences in skin growth.
- Differences in nutrition in the womb – If one twin receives slightly more nutrition than the other through the umbilical cord and placenta, their development may differ slightly.
- Position in the womb – If one twin occupies a position that allows it to move more freely than the other, this can cause subtle differences in development.
- Time of splitting – Twins that split earlier in development will have more time for their fingerprints to develop independently.
While these differences are tiny, research shows they are enough to cause variation in the microscopic ridges and furrows that make up fingerprints. Even the slightest difference means the patterns that emerge will differ.
Studies on Twins’ Fingerprints
Several studies have compared the fingerprints of identical twins to evaluate their similarity:
- In a 1999 study, researchers analyzed the fingerprints of 96 pairs of identical twins. No two twins were found to have identical fingerprints or even similar print patterns.
- A 2015 study used high resolution microscopy to image the fingerprints of three pairs of identical twins at a microscopic level. Unique differences were observed in the ridge structures of each set of twins.
- In 2018, researchers performed fingerprint analysis on 66 pairs of identical twins. Though some visual similarities were noted, upon close inspection the ridge patterns and minutiae points differed.
These studies confirm that while genetics determine the basic development of fingerprints, random variability during fetal development means that even identical twins end up with unique fingerprints.
Fingerprint Analysis
Fingerprint analysis relies on the fact that no two fingerprints are alike. Analysis involves comparing fingerprints found at a crime scene to the fingerprints of suspects. The main points of comparison are:
- General pattern – The overall fingerprint pattern (arch, loop or whorl). This quickly narrows down matches.
- Minutiae – Distinctive features like ridges ending, splitting into two ridges, short ridges or dots.
- Pores – The location and shape of pores found along ridges.
- Creases and scars – Permanent marks on the fingers.
If fingerprints at a crime scene match a suspect’s fingerprints based on these features, it can provide compelling evidence of their identity. The fact that even identical twins have unique fingerprints makes fingerprint identification possible.
Uses of Fingerprint Identification
Because they are unique to each person, fingerprints have many important uses including:
- Criminal investigations – Fingerprints left at crime scenes can identify suspects by matching them to fingerprint databases.
- Security systems – Fingerprint scans are used to access secured buildings, devices and computer systems.
- Immigration – Many countries digitally record entrants’ fingerprints along with other biometric data.
- Healthcare – Patients’ fingerprints help accurately match them to medical records and identify unconscious patients.
- Banking – Fingerprint authentication improves security for activities like opening accounts and authorizing payments.
In all these applications, fingerprints provide a reliably unique biometric identifier because even identical twins have distinctive fingerprints.
Conclusion
While identical twins originate from the same fertilized egg and share the same DNA, their eventual fingerprints differ in the details. Slight variation in their fetal development and womb environment means the microscopic ridges and furrows that make up fingerprints will not be identical. Studies comparing twins’ prints conclusively show that even genetically identical people do not have the same fingerprints. The individuality of fingerprints is why fingerprint analysis is such a useful biometric technique for identification and security.