The color of the iris is formed by coloring pigments (melanocytes) and depends on their concentration in the stroma. If a small amount of coloring pigment is produced, the eyes will most likely be light (blue or gray). In people with brown and black eyes, melanocytes in the stroma are located in large quantities. The number of cells producing coloring pigment is determined at the level of genotype formation and is a hereditary factor.

Many newborns are born with a light blue iris. This happens due to the fact that the mechanism of melanin production has not yet been fully established. Around six months, the number of melanocytes increases and the baby's eyes may change color to a darker one. If a baby is born with brown eyes, the possibility that they will eventually become blue is zero, since brown is the predominant color, and blue is weaker (recessive).

Mechanisms of inheritance of eye color in humans

It is impossible to predict with absolute accuracy what color the baby’s iris will be. Mendel's laws say that iris color is inherited in the same way as hair color. Programming genes dark colors, are considered stronger (dominant), and the genes that create a light color are considered weaker. When forming a phenotype dominant gene takes over the recessive giving the eyes a stronger and more saturated color

Basic situations of gene interaction

Brown-eyed parent and blue-eyed parent (AA and aa)
The child of such a couple will have the genotype Aa, which means that the genotype of his brown-eyed father is AA, and his mother is aa. During the merger, the dominant genes interacted with the recessive ones and created the Aa pair, where the father's genes predominate. The probability that a child's eyes will be brown is 90%. There are exceptions, mostly girls, for some reason, fall under them, so the possibility of having a blue-eyed baby is also quite real, although only in 10% of general cases.

Brown-eyed parent (genotype Aa) and blue-eyed parent (aa)
In this situation, after the merger, the following four genotypes will appear: Aa, Aa, aa, aa. The chances of both genotypes are equal, since the probability of having a brown-eyed or blue-eyed child is the same (50 to 50).

Brown-eyed parents (genotype Aa)
In this case we see the formation of three pairs dominant genotype Ah, so in 75% of cases this couple will have a child with brown eyes.

Both parents with blue eyes (genotype aa)
In such a tandem, the probability of giving birth to a child with eyes like their parents is almost 100%, since the genotype of this couple absolutely does not contain the dominant gene “A”, which is responsible for dark color iris.

In relation to himself rare color eyes - green, blue will dominate, forming, so the probability of having a baby with green eyes will be 40%. If one parent has brown eyes, and the other is green, their child:

• in 50% of cases, be born with brown eyes;
• in 37% of cases with greens;
• and in 13% of cases will have Blue eyes.

Recently, genetic scientists have identified 4 additional genes that affect the mechanism of inheritance of iris color. It was found that the genes of the ancestors, as well as their ancestors up to the 16th generation, are also responsible for the mechanism of formation of the color of the iris. Therefore, if parents with brown eyes give birth to a child with sky-colored eyes, this may be the result of a predominance of the grandparents' genes.

The mechanism of color inheritance is a rather complex genetic process, which is determined by the interaction of dominant and recessive genes. The formation of the number of melanocytes and their location as well as others hereditary factors and geographic location of a person.

Blue and green, their inheritance results in two pairs of genes. The shades of these colors are determined individual characteristics The body distributes melanin in chromatophores, which are located in the iris. Other genes that are responsible for hair color and skin tone also affect the shade of eye color. For blond people with fair skin are typical, and representatives of the Negroid race have dark brown eyes.

The gene that is responsible only for eye color is located on chromosome 15 and is called HERC2, the second gene - EYCL 1 is located on chromosome 19. The first gene carries information regarding brown and blue color, the second is about green and blue.

The dominant color in the HERC2 allele is brown, the dominant color in the EYCL 1 allele is green, and blue eyes are inherited in the presence of a recessive trait in two genes. In genetics, it is customary to designate dominant capital letter Latin alphabet, the recessive trait is a lowercase letter. If a gene contains capital letters and lowercase letters- the organism is heterozygous for this trait and has a dominant color, but a hidden recessive trait can be inherited by a child. A “suppressed” trait will appear in a baby when an absolute recessive allele is inherited from two parents. That is, parents may well have a blue-eyed child or with.

Using latin letters, brown eye color, which is determined by the HERC2 gene, can be designated AA or Aa, blue eyes correspond to the set aa. When a trait is inherited, the child receives one letter from each parent. Thus, if dad has a homozygous trait of brown eyes, and mom has blue eyes, then the calculations look like this: AA+aa=Aa, Aa, Aa, Aa, i.e. a child can only achieve the Aa set, which manifests itself according to the dominant, i.e. the eyes will be brown. But if the father is heterozygous and has the Aa set, and the mother is blue-eyed, the formula looks like: Aa+aa=Aa, Aa, aa,aa, i.e. there is a 50% chance that a child with a blue-eyed mother will have the same eyes. U blue-eyed parents the eye inheritance formula looks like: aa+aa=aa,aa, aa, aa, in this case the baby inherits only the recessive allele aa, i.e. his eye color will be blue.

In the EYCL 1 allele, eye color is inherited in the same way as in the HERC2 gene, but only the letter A denotes green. Nature arranges it in such a way that the existing dominant trait of brown eyes in the HERC2 gene “defeats” the existing green trait in the EYCL 1 gene.

Thus, a child will always inherit brown eye color if one of the parents has a homozygous dominant set of AA in the HERC2 gene. If a parent with brown eyes passes on the recessive gene a to the child, i.e. a sign of blue eyes, then the color of the eyes determines the presence of a green dominant trait in the EYCL 1 gene. In cases where a parent with green eyes does not transmit the dominant trait A, but “gives” the recessive allele a, the child is born with blue eyes.

Since eye color is determined by two genes, its shades are obtained from the presence of undetected characteristics. If a child has the AA genetic set in the HERC2 allele, then the eyes will be dark brown. Presence of the trait in the HERC2 gene brown eyes by type Aa, and in the EYCL 1 gene of the recessive trait aa, causes light brown eyes. Homozygous trait green eyes AA in the EYCL 1 locus determines a more saturated color than the heterozygous set Aa.

Many mothers, while expecting a baby, often think about how he will be born, what color eyes and hair he will have, what nose, lips and height he will have. Will he look like his parents or will he inherit the features of one of his relatives? Genetics can provide answers to these questions even before the baby is born.

Based on the laws of genetics, let's look at the algorithms by which a child's appearance is most often formed.

Eye color

If dad has dark brown eyes and mom has blue eyes, then the child has high probability There will be brown eyes. The gene for brown eyes is dominant (strong), and the gene for blue eyes is recessive (weak). If both parents have brown eyes, then they are unlikely to have a child with green, gray or blue eyes. Time will pass- and they will begin to darken, gradually turning into brown.

But if both parents are blue-eyed, then the baby will most likely have blue eyes.

Dominant traits

If at least one parent has dimples on the cheeks, a hooked (or large/crooked) nose, or protruding ears, then there is a very high probability that the child will also have this appearance feature. The fact is that these, as we commonly believe, shortcomings are dominant signs and “peck out” in the baby’s appearance.

But, as a rule, only one such feature appears, less often - two at once.

Hair color

The gene for dark hair outweighs the gene for light hair because its pigment is strong. If both parents are fair, then the baby will also be born blonde or light brown. And if dad is a bright brunette, and mom is blonde, then the baby’s hair will be dark or light brown.

Interesting fact: a child who was born dark from this combination may have light-colored children in the future. The fact is that children of mixed genes receive both a strong gene from their father and a weak gene from their mother. Later, the weak gene can “merge” with the weak gene of the partner - and the child’s appearance will be light.

Also, the child may be completely different from you if he inherits wandering genes distant relatives. Thus, in a brown-haired family, a red-haired baby may suddenly be born, and there are also cases when a dark-skinned child was born to white-skinned parents, even if there were mulattoes in the family even several generations ago.

Source: instagram @sarahdriscollphoto

Curly or smooth hair

Wavy and curly hair is also a dominant trait that is most likely to appear in a child if at least one of the parents has it.

A question that many parents ask. However, it is impossible to answer this question unequivocally, since the answer depends 90% on genetic predisposition and 10% on chance.

Only one thing is clear here - the baby will be born with cloudy gray-blue or dark brown eyes.

What color will my child's eyes be?

Almost always, the eyes of newborns have a blue color, which subsequently, starting from 6 months, begins to change and darkens as it is exposed to sunlight(although for most children this occurs between 6 months and one year of age). Around the age of three or four, the child’s eyes acquire their permanent color that remains for life.

Predicting a child's eye color

Below is a diagram that shows the “chances of success” of a particular eye color (in % ratio) depending on the eye color of the parents.

Also look at the site - determining the color of a child’s eyes by the eye color of the baby’s parents and the eye color of your parents. This is an English-language resource, but it won’t be difficult to figure out what’s what.

How reliable is this? Let's check it together! Please let us know in the comments whether the eye color in reality coincided with the predictions calculated and proposed using these methods.

Inheritance of eye color from a genetic point of view

The color of a child's eyes is determined by the parents' genes, but great-grandparents also contribute to the child's appearance. It turns out that their colors and shades have a polygenic inheritance pattern and are determined by the number and types of pigments in the iris cornea of ​​the eye.

In general, the color of a person’s eyes depends on the amount of melanin in the iris (melanin is also responsible for the color of our skin). In the spectrum of all possible variety of colors, one extreme point will be blue eye color (the amount of melanin is minimal), and the other is brown (the maximum amount of melanin). People with different eye colors fall somewhere between these extremes. And the gradation depends on the genetically determined amount of melanin in the iris.

Genetic studies show that the pigment component of the iris is controlled by 6 different genes. They interact with each other according to certain clear patterns, which ultimately leads to a wide variety of eye colors.

There is an established opinion that a child’s eye color is inherited according to Mendel’s laws - eye color is inherited in almost the same way as hair color: genes dark color are dominant, i.e. distinctive features (phenotypes) encoded by them take precedence over distinctive features, encoded by the lighter color gene.

Parents with dark hair, most likely, the children will also have dark hair; the offspring of blond parents will be blond; and a child of parents whose hair color is different will have hair whose color will be somewhere in between the parents'.

However, the idea that brown-eyed parents can only have brown-eyed children is a fairly common misconception. A brown-eyed couple may well have a blue-eyed child, especially if one of the close relatives has a different eye color). The fact is that a person copies two versions of one gene: one from the mother, the other from the father. These two versions of the same gene are called alleles, with some alleles in each pair being dominant over the others. When we're talking about about the genes that control eye color, brown will be dominant, however, the child can also receive a recessive allele from either parent.

Let us note some patterns in the inheritance of eye color by a child:

• Your husband and you have blue eyes - 99% that the child's eyes will be exactly the same color or light gray. Only 1% gives the chance that your baby will have green eyes.
• If one of you has blue eyes and the other green, then the child’s chances of having both eye colors are equal.
• If both parents have green eyes, then there is a 75% chance that the baby will have green eyes, a 24% chance of blue eyes, and a 1% chance of brown eyes.
• The combination of blue and brown eyes in parents gives a 50% to 50% chance for the child to have one or the other eye color.
• Brown and green parental eyes are 50% of children's brown eyes, 37.5% of green eyes and 12.5% ​​of blue eyes.
• Both parents have brown eyes. This combination will give the baby the same color in 75% of cases, green in 19%, and only in 6% babies can be blue-eyed.

Some fun facts about eye color

• The most common eye color around the world is brown.
• the most rare color Less than 2% of the world's population has a green eye.
• Türkiye has the highest rate percentage citizens who have green eyes, namely: 20%.
• For residents of the Caucasus, blue eye color is the most characteristic, not counting amber, brown, gray and green. Also, more than 80% of Icelandic residents have either blue or green eye color.
• There is such a phenomenon as heterochromia (from the Greek ἕτερος - “different”, “different”, χρῶμα - color) - different color of the iris of the right and left eyes or unequal coloring of different parts of the iris of one eyes.

Now you know what color your child’s eyes will be, and we, in turn, wish that, regardless of color, there is only happiness and joy in his beloved eyes!

We do not choose the color of our eyes, the shape of our ears and nose - these and many other features are inherited from our parents and distant ancestors, the existence of which we can only guess. The quality of vision, hearing or smell does not depend on the shape of the organ of perception, but family traits are sometimes something like a certificate of membership in a clan. Some families are famous for their tall stature, while in others the “trick” is protruding ears or club feet. The inheritance of eye color is not one of the strictly transmitted traits, but there are still certain patterns.

Eye color: diversity and genetics

There are 7 billion people living on Earth, each of whom has a set of individual traits. The color of the iris is one of the features that practically does not change in an adult, although in older people it loses its brightness.

Scientists counted several hundred possible shades and classified them. For example, according to the Bunak scale, the rarest are yellow and blue irises. The Martin Schultz scale classifies black eyes as rare. There are also anomalies: in albinos with complete absence white iris pigment. Interesting research on how the unequal color of two eyes is inherited.

Formation of iris color

The iris consists of two layers. In the anterior, mesodermal layer, there is stroma, which contains melanin. The color of the iris depends on the distribution of the pigment. The color of the posterior, ectodermal layer is always black. The exception is albinos, who are completely devoid of pigments.

Basic colors:

Blue and cyan

The iris fibers are loose and contain a minimum of melanin. There is no pigment in the shells; reflected scattered light creates the impression of blue. The thinner the stroma, the brighter the azure. Almost all people are born with heavenly eyes; this is the common eye color for all babies. Genetics in humans manifests itself towards the end of the first year of life.

In blue-eyed people, the whitish collagen fibers in the stroma are more densely distributed. The first blue-eyed people appeared on the planet about 10,000 years ago thanks to a gene mutation.

Blue-eyed people inhabit mainly the north of Europe, although they are found throughout the world.

Grey

At high density collagen in the outer layer of the iris shell is gray or blue-gray. Melanin and other substances can add yellow and brown impurities to the color of the iris.

Many gray-eyed people live in the north and east of Europe.

Green

It appears when yellow or light brown pigment and diffused blue or cyan are mixed. With this coloring, many shades and uneven distribution across the iris are possible.

Pure green is very rare. The best chances to see them are in Europe (Iceland and the Netherlands) and Turkey.

Amber

The yellow-brown iris may have a greenish or copper tint. There are very light and dark varieties.

Olive (walnut, green-brown)

The shade depends on the lighting. Formed by mixing melanin and blue. There are shades of green, yellow, brown. The color of the iris is not as uniform as amber.

Brown

If there is a lot of pigment in the iris, a brown color of varying intensity is formed. People with such eyes belong to all races and nationalities; brown-eyed people make up the majority of humanity.

Black

When the concentration of melanin is high, the iris is black. Very often eyeballs in black-eyed people they are yellowish or grayish. Representatives of the Mongoloid race are usually black-eyed, even newborns are born with an iris saturated with melanin.

Yellow

A very rare phenomenon, it usually occurs in people suffering from kidney disease.

How is eye color inherited?

The inheritance of eye color in humans is beyond doubt among geneticists.

• Light is formed due to a mutation in the OCA2 gene.
• Blue and green - EYCL1 gene of chromosome 19.
• Brown - EYCL2.
• Blue - EYCL3 chromosome 15.
• And the genes SLC24A4, TYR are also involved in formation.

According to the classical interpretation, the heredity of eye color occurs as follows: “dark” genes dominate, and “light” genes are recessive. But this is a simplified approach - in practice, the probability of inheritance is quite wide. The combination of genes determines eye color, but genetics can present unexpected variations.

Eye color is inherited

Almost all human babies are born with blue eyes. Inheritance of eye color in children appears approximately six months after birth, when the iris acquires a more pronounced color. By the end of the first year, the iris is filled with color, but final formation is completed later. In some children, the eye color determined by genetics is established by the age of three or four, while in others it is formed only by ten.

Inheritance of eye color in humans appears in childhood, but with age the eyes may become pale. In old people, pigments lose their saturation due to degenerative processes in the body. Some diseases also affect eye color.

Genetics is a serious science, but it cannot say with certainty what kind of eyes a person will have.

90% of the probability of eye color is determined by hereditary factors, but 10% should be left to chance. Eye color (genetics) in a person is determined not only by the color of the iris of the parents, but also by the genome of ancestors up to the fifth generation.

Eye color (genetics) in a child

The established idea that eye color is literally inherited is erroneous and outdated. A child of a brown-eyed father and mother may well be blue-eyed if one of the grandparents or more distant ancestors had light eyes.

To understand how eye color is inherited, it should be taken into account that each person inherits the genes of his mother and father. In these pairs - alleles, some genes can dominate over others. If we talk about a child’s inheritance of eye color, the “brown” gene is dominant, but the “set” may consist of recessive genes.

Probability of a child's eye color

It can be predicted with a high degree of certainty that the child will be born blue-eyed, but the iris will change with age. It’s definitely not worth drawing conclusions at birth, since the inheritance of eye color in children does not appear immediately.

For many years, geneticists could not come to a common opinion on how eye color is inherited in children. The most convincing hypothesis was that of the Austrian biologist and botanist Gregor Johann Mendel, who lived in the 19th century. The abbot in his teaching, using the example of inheritance of hair color, suggested that dark genes always dominate light ones. Subsequently, Darwin and Lamarck developed the theory and came to a conclusion about how eye color is inherited.

Schematically, the patterns of inheritance of eye color by children can be described as follows:

• Brown-eyed or black-eyed parents will have dark-eyed children.
• If the parents are light-eyed, the child will inherit their eye color.
• A child born from parents with dark and light eyes will inherit a dark (dominant) or medium iris color.

Science, which grew from these observations and generalizations, has most accurately calculated the heredity of eye color in children. Knowing how eye color is inherited, you can fairly accurately determine which eyes your descendant will inherit.

How is eye color inherited in children?

There cannot be one hundred percent certainty in one result, but the child’s likely inheritance of eye color can be predicted quite accurately.

Eye color (genetics) in a child:

1. With two brown-eyed parents, a child inherits their eye color in 75% of cases, the probability of getting green is 18%, and blue is 7%.
2. Green and brown eyes of father and mother determine the inheritance of eye color by the child: brown - 50%, green - 37%, blue - 13%.
3. Blue and brown eyes of mom and dad mean that the child should not have green eyes. The child can be brown-eyed (50%) or blue-eyed (50%).
4. For a green-eyed couple, the likelihood of having a baby with brown eyes is very small (1%). Eyes will be green (75%) or blue (24%).
5. A child born from a union of green-eyed and blue-eyed partners cannot have brown eyes. Eye color (genetics) is equally likely to be green or blue.
6. And also cannot be born brown-eyed child with blue-eyed parents. With 99% accuracy, he will inherit his parents' eyes and there is a small chance that his iris will be green (1%).

Interesting facts about eye color. Genetics in practice

• Most people on Earth have brown eyes.
• Only 2 percent of people look at the world with green eyes. Most of them are born in Turkey, but in Asia, the East and South America This is a real rarity.
• Many representatives of the peoples of the Caucasus have blue eyes.
• Icelanders are a small nation, but most of them are green-eyed.
• Eyes different colors- an almost unique phenomenon, but it is not a pathology. Multicolored eyes always attracted attention.
• Grass-colored eyes are often combined with red hair. Perhaps this explains the uniqueness - the Inquisition considered red-haired and green-eyed girls to be witches and mercilessly exterminated them.
• The iris of albinos is practically devoid of melanin; blood vessels, so the eyes turn red.
• At birth, a person receives eyes of a ready size. The ears and nose continue to grow slowly throughout life, but the eyeballs remain the same.
• All blue-eyed people share a common ancestor. Genetic mutation as a result of which the first blue-eyed man appeared, appeared from 6 to 10 thousand years ago.

It is difficult to predict exactly what the eyes of an unborn child will be like, because it is not always possible to take into account all hereditary factors. The color of the iris can change until the age of ten - this is within normal limits.