Blue eyes proven to be a common ancestral mutation

That's right - all people with blue eyes can be linked to 1 common ancestor, from which a mutation occurred in the eyes where there was an underproduction of melanin. This lack of melanin is what turns traditionally brown-eye genetics to blue eyes, and to an extent, affects the hair colour of said individual. The colour of hair, for example, is determined by the amount of melanin contained within in; the more melanin, the darker the colour. This also applies to skin.

The complete lack of melanin is known as Albinism.

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