The eye colors of the mother and father partially determine a baby's eye color, explains BabyMed. However, many genes work together to affect eye color, so there are no simple rules to inheritance.
Eye color is a polygenic trait; this means that many genes work together to influence it. The actual genetics of parental eye colors plays a large role, according to BabyMed. For example, if both parents are homozygous for brown eyes, meaning they each have two copies of the brown-eyed gene, they might expect brown-eyed children. But if the parents are heterozygous for eye color, meaning they each have a brown and a blue gene, they could expect some children to have blue eyes.
Eye color is also dependent on the ratios and amounts of melanin types deposited on the eye. Eumelanin is a dark brown pigment, and pheomelanin is reddish brown, and the manner in which they occur in the iris determines eye color. This means that if the production and dispersal of pigment do not work properly in an individual, the person could have the genes for brown eyes but physically have blue eyes. This accounts for cases of two blue-eyed parents having children with green, hazel or brown eyes, reports John H. McDonald of the University of Delaware.