Genes are subunits of deoxyribonucleic acid, or DNA. All of a person’s physical traits are controlled by genes. These genes are handed down from a mother and father when a child is conceived. The genes handed down originally came from the newly conceived child’s grandparents, great-grandparents, and so on. It is possible, although unlikely, that a child may be born with his or her great grandmother’s green eyes, even if no one else in the immediate family has them.
Although the science behind eye color is very technical, it can be simplified into the idea that each person has two eye color genes provided by their parents. In a male, this would be represented as BG, representing the potential for brown and green eyes. In a female it would be BBl, brown and blue. Between a set of parents, a child could have blue, green, brown, or some combination, such as hazel. Each parent will randomly send one of these genes with either the sperm or egg used to create the fetus.
Some eye color genes are more dominant than others. If a child has brown and blue eye color genes, it is highly likely that the child will have brown eyes. This is because brown eye genes are dominant over blue eye genes. Dominant and recessive genes also determine characteristics such as vision, hair color, dimples, finger and toe length, and some health conditions. Dominant genes usually become the visible characteristic.
To make things more difficult, there are actually several genes that contribute to eye color. Each of these genes controls an aspect of eye color, such as how dark the eye color is. This makes it even more difficult to determine eye color. A child born with blue eyes could have very light blue eyes, dark blue eyes, or any shade of blue in between.
The majority of infants are born with blue eyes. After a few months, and up to a couple years in some cases, the eyes of most of these infants will change to the color that the eyes will be in adulthood. It is very possible that the parents will not know the true eye color of their child until that child is a year or two old. In the case of two brown-eyed parents, though, it is most likely that the child will have brown eyes. If both parents have the same eye color, their children will probably have the same color. If the parents have different eye colors, the child will probably have the dominant eye color. It is still possible, though for the child to end up with the recessive eye color, or even a different color altogether if there is a history of that color in the family.
