How Fingerprints Develop and Why they are Unique.

The areas of skin which provide a fingerprint is known as Friction Ridge Skin. Friction Ridge Skin develops between 6 and 24 weeks of foetal development.

Around 6 weeks, the hands begin to take shape and bulges appear which are known as volar pads. It is the internal and external pressures and stresses within the womb that affect the development of these bulges and along with genetics help determine the patterns of the fingerprints.

At around 8 weeks the fingers seperately and the three main creases of the palm appear. At around 13 weeks the volar pads start to regress.

Friction Ridge Skin is composed of 2 layers - an inner layer called the dermis and an outer layer called the epidermis. The epidermis consists of four layers, the top layer being the surface of the friction ridge skin which is constantly shredding and the bottom layer known as the generating layer. The generating layer is constantly replacing the top layer which has previously shed.

At 13 weeks, ridges begin to form in the generating layer. Due to a combination of genetics and various stresses exerted on the developing foetus which are so unpredicable and unique to that pregnancy that it is impossible to replicate. The generating layer will continue to generate the same friction ridge structure throughout life and the friction ridge structure will remain unchanged. This is how every fingerprint is unique , including those of twins.

At 24 weeks of foetal development the friction ridge skin is fully formed and is persistent throughout life.