Barbara Marquand is a staff writer at NerdWallet, a personal finance website. Email: bmarquand@nerdwallet.com. Twitter: @barbaramarquand.
The eye may change color due to alteration of genes in the cells of the iris. This is because of your DNA factors in the body. The gene alteration can cause the eye to change color from brown to green and vise verse. There is no any explanation to the cause of the genes behaving in these manner. Prolonged exposure to the sun might also be another cause that made my eyes to change the color.
Melanin. At the most basic level, the answer to what causes eye color is the pigment melanin. Because melanin isn't fully present at birth, many babies have blue eyes at birth that will later change to brown or green. Melanin can deposit in either the front or back layer of the iris.ris color can vary widely. Eye color in humans varies from very light to very dark. Eye color should more accurately be called iris color, since the iris, the central part of the eye, contains the different colors.