Why are brown eyes more common than other eye colours?
Brown eyes are more common due to genetics: Brown eyes are autosomal dominant, meaning you only need one allele (not two) to have brown eyes. Green and blue eyes are autosomal recessive, meaning you require both alleles to be recessive to get this eye color(s). Lighter eyes are more common in Europe because there are not as many brown-eyed people mixing up their majority of recessive genes.
