Baby eye color - when is it final?

introduction

The iris, which makes up our eye color, has deposits of melanin. Melanin is a color pigment that is not only responsible for the color of our eyes, but also the color of our hair and skin. Depending on how much melanin is stored in the iris, a different eye color is created.

The melanin can reflect or absorb certain wavelengths of light, depending on the extent to which it does this, the three classic eye colors blue, brown and green arise. The melanin in our eyes serves to protect against solar radiation. Accordingly, a stimulus for the melanin production is the contact of the eyes with sun rays, so that the melanin production is only really boosted in the course of the first years of life and consequently the eye color can still change.

Read more about this under How does eye color come about?

Causes of lighter eye color

For a light eye color like blue, you need relatively few pigments. The less melanin is stored in the eyes, the brighter the eyes appear. In people with light eye colors, genes are inherited that have little or no ability to produce melanin. Because melanin is a protective factor against exposure to the sun, people with blue or light eyes are more sensitive to light. If a little more pigment is stored than in blue eyes, green eyes develop.

When is the final eye color created?

Newborn babies usually have blue eyes, or rather eyes that appear blue, to begin with. Because the baby's eye color isn't really blue. This is due to the fact that the iris of the eye, which is responsible for the color of the eyes, only receives a few light rays in babies, because so far only a few pigments / little melanin has been stored. The result is that many rays of light are thrown back because no absorption can take place. This makes the iris appear blue.

The final eye color arises between six months and a year, and the final eye color should be developed by one and a half years at the latest.

If there are still dark or brown spots in babies with blue eyes, this indicates that the eye color is still changing. Because even if the basic eye color is already defined after about a year, with increasing age there can still be different shades and shades of the basic color blue, gray, brown or green, so that individual eye colors are created.

Can you influence the baby's eye color?

You cannot influence the baby's eye color as it is genetically determined. The genetic make-up dictates how much melanin pigment is produced. This is ultimately responsible for the pigmentation of the iris in the eye and thus for the color of the baby's eyes.
It is assumed that there is an evolutionary biological connection with the eye color. In areas with a lot of solar radiation (e.g. Africa, Southern Europe), the population tends to have dark eyes on average, in colder areas (e.g. Scandinavia) blue eyes are also more common. Dark eyes provide protection from the sun and have probably become established in Africa, among others.

Can you calculate the eye color before birth?

The eye color is genetically determined and depends on the eye colors of both parents. However, the final eye color of the newborn cannot be calculated exactly, only probabilities can be given. The genes determine how much melanin is produced. Each gene is present in two copies (alleles) (diploid). One allele comes from the mother, the second from the father. The trait for brown eyes is inherited dominantly, while the trait for blue eyes is inherited recessively. Dominant means that one copy of the trait is enough for the child to ultimately have brown eyes. In the case of blue eyes, which are inherited recessively, both copies must have the blue characteristic. If there is only one recessive copy, the feature is "overwritten" by another, dominant copy.

We now know that several genes are responsible for inheriting eye color, so inheritance is a little more complex. Other genes are responsible for the respective color intensities and shades of the individual eye color, for example. Not only brown eyes are inherited dominantly. Green eyes are also passed on as dominant, but less dominant than brown eyes. Blue eyes are passed on recessively. Gray eyes have even less assertiveness than blue eyes, they are also a recessive characteristic.

Parents eye color brown - that of the child blue?

Heredity explains why children whose parents both have brown eyes can also develop blue eyes. The brown eye color is inherited as a dominant trait, while the blue eye color is inherited as a recessive trait. In the case of the parents, it is sufficient if one of the two copies of a gene has the brown trait, because the brown trait always displaces another eye color trait, since it has the strongest dominance. The second copy of the feature can therefore have the blue feature, but this is not expressed. In the case of inheritance, only one copy of a gene, i.e. a characteristic for the eye color, is passed on from mother and father. If the child then has blue eyes, because the gene for blue eyes is recessive, the child must have two copies with the blue characteristic.

Probabilities for the different eye colors

The final eye color cannot be predicted one hundred percent. But different probabilities can be determined based on the eye color of mother and father. If both parents have brown eyes, over 50% of the time the child will also have brown eyes. However, about 20% of the eye color can also be green and almost 10% blue. Since the trait for brown eyes is inherited dominantly, parents with brown eyes can also have the trait for green or blue eyes, which is then not pronounced, but can be inherited.

If one parent has brown eyes and the other has blue eyes, the probability is 50% for brown or blue eyes. The same applies if one parent has brown eyes and the other parent has green eyes.

The best way to predict the likelihood of eye color is when both parents have blue eyes. Then the eye color is blue with almost one hundred percent probability. This is because with blue eyes, both parents must have two blue characteristics so that the child automatically receives two blue characteristics.

If both parents have green eyes, the child has 75% green eyes and 25% blue eyes. Brown eyes are out of the question because one of the parents would have to have brown eyes.

Eye color in Asians

While almost all babies in Europe are initially born with blue eyes, Asian babies are more likely to be born with brown eyes. The same applies to African babies or babies with dark skin. Although Asians are light-skinned, light-colored eyes are not common among them. There is a presumption that the blue eye color arose several thousand years ago through a mutation and was then passed on. This mutation does not seem to have prevailed among Asians, so that it can hardly be found in the genome of Asians.