× Thanks for reading! Log in to continue. Enjoy more articles by logging in or creating a free account. No credit card required. Log in Sign up {{featured_button_text}}

This week’s question was asked by: a parishioner at our church.

QUESTION: What causes my eyes to change from a blue color to a hazel color?

ANSWER: The pupil is that black center of the eye and it is black for everyone. The iris of the eye is that thin circular structure responsible for controlling the diameter and size of the pupil. The iris of the eye is like a diaphragm allowing more light or less light to strike the retina where the image is formed. It is the iris of the eye that is colored.

Eye color is an inherited trait. There was a once-held view that blue eyes were caused by a recessive trait. Eye color is much more complex, involving as many as 14 different genes. The two main genes associated with eye color are located on Chromosome 15.

Pigmentation of the iris in humans varies depending on the amount of melanin, a natural pigment, located in the back of the iris. Most babies of European ancestry have light colored, or blue eyes, at birth. As a child develops, from age one to three, cells in the iris slowly begin to produce melanin. If sufficient amounts of melanin are produced, the eyes turn brown or green.