Among the numerous questions that most future parents ask themselves, is this: “What eye color will my baby have?”
Usually, all children inherit the color of their eyes from the parents. But inheriting the eye color is not so simple as you may assume, and this is because it`s polygenic. This means that the trait is influenced by multiple genes that work together. Even if we are to consider the most obvious gene, there are still several things to take into consideration:
- The eye color of the parents.
- Whether or not the parents are heterozygous or homozygous for that particular color.
- Whether the parents` eye colors are dominant or recessive.
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What Eye Color Will My Baby Have?
The answer isn`t always simple and usually is based on a series of genetic and hereditary factors, that neither the scientists don`t completely understand yet.
The color of a person`s eyes depend on the amount of pigment known as melanin present in the eye`s iris (melanin is also responsible for the skin`s color). Persons with blue eye color have a relatively low amount of melanin, while people with brown eye color have a high amount of melanin. Persons with a different eye color are usually somewhere in these 2 extremes.
A newborn will inherit genes from both the mother and father, and these genes combines may determine eventually the baby`s eye color (more info!). All babies (with a few exceptions) are born with blue/gray or brown/black colors (in general, newborns that have a lighter skin color have a lower amount of melanin and are likely to have blue eyes at birth, while newborns with darker skin, so a higher amount of melanin, will be born with brown/black eye color).
The color of a baby`s eyes can change as their body starts to produce melanin, which may happen any time until the age of 3. For most newborns, the color of the eyes can change around 6 months to 1 year. That`s why, babies with a blue eye color at birth may eventually turn to a brown eye color as they grow.
A common mistake is to think that only babies with brown eyes can come out of parents with brown eyes. Of course, certain combinations of parental eye color increase or decrease the likelihood of the baby having a particular color, but nothing is ever 100% sure.
Dominant vs. Recessive Genes
That`s why, just because both parents have blue or green eyes, it doesn`t mean that the baby will inherit the same color of the eyes. This is because people carry 2 copies for each gene, one from the mother and one from the father. These 2 versions of each gene are known as “alleles” and in some cases some are more dominant than others. In the case of genes that control the eye color, brown is dominant to blue, but a baby may inherit the recessive gene from one or both parents. – Click this link!
If you want to better understand the above details, think of letter “B” is the brown eyes and the letter “b” is the blue eyes (each person has a combination of 2 eye color genes, one inherited from each parent). Because we know that the gene of brown eyes (B) is dominant to the gene of blue eyes (b), then a baby with brown eyes may have either the combination “BB” or “Bb,” while a baby with blue eyes can only have “bb.”
- The father has brown eyes, so he has one of the 2 possible combinations, either “Bb,” or “BB.” The dominant one is brown (B) to blue, so blue is called the recessive gene.
- The mother has blue eyes, then the only possibility she can have is “bb.”
- Thus, so the baby can have blue eyes, the father needs to have 1 pair of gene “Bb” and transmit to the baby the recessive gene “b.” The mother will transmit only transmit 1 gene “b.” The combination resulted for the baby is in this case “bb,” so the baby will have blue eyes.
- If the father would have had the combination “BB,” it wouldn`t been possible for the baby to have blue eyes.
If both parents have brown eyes, while the baby has blue eyes, this means that each parent had a combination of “Bb” type and both have transmitted to the baby the recessive gene, “b.” If at least one parent would have transmitted the dominant gene “B“ to the baby, then the result would have been a baby with brown eyes. – More details!
Genetics is much more complicated than the above examples, and presently it`s considered that there`s a large number of genes (not only 2 or 3) that in the end influence the eye color of each person.