Eye colour
The view that blue eye color is a simple recessive trait is incorrect. Two main gene loci code for the eye pigment: OCA2 and HERC2. They sit next to each other on chromosome 15. Mutations (SNPs) to these genes account for much of the variation seen in eye color. OCA2 mutations close to the 5′ regulatory region explain most human eye-color variation. An intron in HERC2 contains the promoter region for OCA2, affecting its expression.