How the Body Works: Eye Color

The gene that codes for brown eye color is dominant over that for blue. A man with two genes for brown eyes and a woman with two genes for blue eyes will produce all brown-eyed children, each of whom possesses one gene for brown eyes and one gene for blue eyes. If, however, two parents with brown eyes each carry the recessive gene for blue eyes they will produce children in the ratio of one blue-eyed to three brown-eyed.