Q. Why do identical twins have different fingerprints? Why do we have fingerprints to begin with?

A. The probable answers to both questions are related to the minute differences in the mechanical forces each developing fetus experiences in the uterus as its cells proliferate.

Image Credit... Victoria Roberts

Researchers have found that identical twins have a very high correlation of loops, whorls and ridges, but a review study last year in Circulation Research examining how complex structures like the circulatory system develop says that “the detailed ‘minutiae’  where skin ridges meet, end or bifurcate  are different even between identical twins.” Even twins that develop from one zygote occupy different positions in the womb, and the variations are enough to make a difference.

At the crucial stage of development, the study explains, ridges are thought to form as compressive stresses develop in the dermal cell layer of the skin, sandwiched between the epidermis and the subcutaneous tissue. “Like the buckling of land masses under compression,” the study continues, regular ridges form to relieve the stress.