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 darken as it is exposed to sunlight (although in most children this occurs between the ages of 6 months and a year). 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 color of the eyes of the baby’s parents and the color of the eyes 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 the color of a child’s eyes is inherited according to Mendel’s laws - eye color is inherited in almost the same way as hair color: genes for dark color are dominant, i.e. the distinctive features (phenotypes) encoded by them take precedence over the distinctive features encoded by the lighter color gene.

Parents with dark hair are more likely to have children with 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 it comes to genes that control eye color, brown will be dominant, however, a 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 will have 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 has green eyes, then the chances of the child 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 rarest eye color is green - less than 2% of the total population of the Earth.
• Turkey has the highest percentage of citizens with 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 the color, there is only happiness and joy in his beloved eyes!

Solution: Let's write down the crossing scheme.

R: ♀ aa x ♂ Aa

blue brown

G: (a) (A) , (a)

brown blue

Answer: the probability of having a blue-eyed child is 50%.

Task 2. Phenylketonuria is inherited as an autosomal recessive trait. In a family where both parents were healthy, a child with phenylketonuria was born. What is the probability that the second child in this family will also be sick?

Solution. R: ♀ A- x ♂ A-

Reasoning. Since both parents are healthy, they can have both the AA and Aa genotypes. Since the first child in this family was sick, his genotype is aa. According to the gamete purity hypothesis, the body receives one allele of a gene from the father, and the other from the mother. Consequently, both parents are heterozygous for the analyzed trait - Aa.

Now you can determine the probability of having a second child with a patient:

R: ♀ Aa x ♂ Aa

Norm norm

G: (A), (a) (A), (a)

F 1: AA, 2 Aa, aa

Normal normal phenylketonuria

Thus, 75% of children will be healthy, and 25% will be sick.

Answer: 25%.

Task 3. In some breeds of cattle, polledness is dominant over hornedness.

A) When crossing polled and horned animals, 14 horned and 15 polled offspring were born. Determine the genotypes of the parental forms.

C) As a result of crossing horned and polled animals, all 30 offspring were polled. Determine the genotypes of the parental forms.

C) Crossing polled animals with each other produced 12 polled and 3 horned calves. Determine the genotypes of the parental forms.

Solution. The genotypes of the parents can be determined by segregation in the offspring. In the first case, the splitting was 1:1, therefore there was an analyzing cross:

R: ♀ Aa x ♂ aa

polled horniness

G: (A), (a) (a)

polled hornedness

In the second case, there was uniformity of the offspring, therefore homozygous horned and polled animals were crossed:

R: ♀ AA x ♂ aa

Norm norm

polled

In the third case, a 3:1 split occurred, which is only possible when crossing two heterozygotes:

R: ♀ Aa x ♂ Aa

polled polled

G: (A), (a) (A), (a)

F 1: AA, 2 Aa, aa

polled hornedness

75% - polled

25% - horned

Answer: A) Aa and aa

B) AA and aa

C) Aa and Aa

Task 4. In humans, brown eyes dominate over blue ones, and right-handedness dominates over left-handedness.

1. What is the probability of having a left-handed, blue-eyed child in a family where the mother is blue-eyed and right-handed (although her father was left-handed), and the father has brown eyes and is predominantly left-handed, although his mother was blue-eyed and right-handed?

2. In a family of brown-eyed, right-handed people, a left-handed child with blue eyes was born. What is the probability that your next child will be right-handed and have blue eyes?

♂--вв ♀ааВ-

R: ♀ aaB- x ♂A-bb

Reasoning. First you need to determine the genotypes of the parents. Since the woman’s father was left-handed, she is therefore heterozygous for the B gene; the man is heterozygous for gene A, since his mother had blue eyes.

Examination. Let's write down the crossing scheme:

R: ♀ aaVv x ♂Aavv

Blue, right Car., lion.

G: (аВ), (ав) (Ав), (ав)

F 1: AaBv, aaBv, Aavv, aavv

Kar., right. Goal, right Kar, lion. Blue, lion

Answer: the probability of having a blue-eyed, left-handed child is 25%.

R: ♀ A-B- x ♂ A-B-

Brown-eyed Brown-eyed

Right-handed right-handed

Blue-eyed lefty

Reasoning. Since, according to the gamete purity hypothesis, the organism receives one gene allele from one parent, and the other from the other, then both parents are heterozygous for both pairs of analyzed genes; their genotype is AaBb.

P: ♀ AaBv x ♂ AaBv

Kar. Right Kar. Right

Thus, the probability of having the next right-handed child with blue eyes (genotype aaBb or aaBB) is 3/16 (or 18.75%).

Answer: 18.75%.

TASKS FOR INDEPENDENT SOLUTION

1. In oats, normal growth dominates over gigantism. A heterozygous plant with normal growth was crossed with a giant one. Determine the genotypes and phenotypes of the offspring.

2. The presence of a white strand of hair above the forehead is determined by a dominant autosomal gene. In a family where the father had a gray strand of hair and the mother did not, a son was born with a white strand of hair above his forehead. Determine the probability of the next child being born without a gray strand of hair.

3. In humans, long eyelashes and cataracts are determined by dominant autosomal unlinked genes. A man with short eyelashes and cataracts and a woman with long eyelashes and normal vision entered into marriage. It is known that only the man’s father suffered from cataracts, while his mother had normal vision and had short eyelashes. The first child in the family was born with short eyelashes and normal vision. Determine the probability of the next child being born with cataracts.

4. The ability to taste phenylthiourea is determined in humans by a dominant autosomal gene. Polydactyly is another dominant gene. Both genes are located on different chromosomes.

A) Determine the probability of the appearance of children with polydactyly in a family of heterozygous parents.

B) In the family, the father has polydactyly, is able to taste phenylthiourea and is heterozygous for both pairs of genes, and the mother is healthy and does not taste phenylthiourea. Determine possible genotypes and phenotypes of children from this marriage.

5. Humans have two forms of hereditary deafness, determined by recessive genes. Determine the probability of sick children appearing in a family where:

A) both parents suffer from the same forms of deafness, and they are heterozygous for another pair of genes;

B) the parents suffer from different forms of deafness, and are they also heterozygous for another form of the disease?

6. In Drosophila, the rugged wing margin and forked setae are determined by recessive unlinked autosomal genes. The laboratory acquired flies with normal wings and straight bristles.

A) how can you be sure that the acquired individuals do not carry the genes for rugged wing margins and forked setae?

B) determine the possible genotypes and phenotypes of the offspring from crossing heterozygous flies with a cut wing and straight bristles and flies with a normal wing and forked bristles.

C) A line with a jagged wing and forked setae and a line with a normal wing and straight setae are crossed. 78 F 1 fruit flies were obtained. 96 descendants were obtained from crossing them with each other. How many types of gametes do flies form from F 1? How many F 1 flies are heterozygous? How many F 2 flies are not capable of producing offspring with jagged wings and forked setae when crossed with completely recessive individuals?

7. In chickens, the genes for black plumage and the presence of a crest dominate over the genes for brown color and the absence of a crest. A) Black crested hen and rooster are crossed. The offspring produced 16 chickens - 8 black crested, 3 black without crest, 4 brown crested and 1 brown without crest. Determine the genotypes of the parental forms. B) Black crested hen and rooster are crossed. All offspring (17 chicks) are similar to their parents. Determine the genotypes of the parental forms. C) A black crested hen and a brown rooster without a crest are crossed. 16 chickens were obtained: 4 black crested, 3 black without crest, 4 brown crested and 5 brown without crest. Determine the genotypes of the parental forms. D) A black crested hen and a brown rooster without a crest are crossed. 17 chickens were obtained: 9 black crested and 8 brown crested. Determine the genotypes of the parental forms.

8. In dogs, the genes for black coat color, hard coat and floppy ear are dominant over the genes for brown coat, soft coat and erect ear. At the kennel, a brown soft-haired puppy with erect ears appeared from crossing a black soft-haired dog with a floppy ear and a brown wire-haired male with a floppy ear. Determine the genotypes of the parent dogs and the likelihood of them having offspring with brown hair.

9. Gray hair is a dominant autosomal trait. In the family, the mother has a strand of gray hair, and the father is healthy. Determine the probability of having children with gray hair in this family if it has been established that the mother is heterozygous for this trait.

10. The ability to taste phenylthiourea is a dominant trait, the gene for which is located on the autosome. In a family of parents who sense the taste of phenylthiourea, a daughter was born who does not sense it. To determine the likelihood of children in the family experiencing the taste of phenylthiourea. What is the likelihood of them having grandchildren who are unable to sense this taste?

11. In guinea pigs, the gene for shaggy hair is dominant over the gene for smooth hair. By crossing two breeds of pigs, one with shaggy fur and the other with smooth hair, 18 furry babies were born. Later they were crossed with each other and got 120 descendants. How many F 2 offspring are heterozygotes?

12. In oats, early ripeness dominates over late ripeness. The gene that determines this trait is located on the autosome. Two heterozygous early ripening plants are crossed. There are 900 plants in the offspring. How many F 1 plants have the trait of late ripening? How many early maturing plants will be homozygous?

13. Hereditary blindness in some dog breeds is a recessive autosomal trait. A pair of dogs with normal vision gave birth to 3 puppies, one of which turned out to be blind. 1) One of the normal puppies from this litter was allowed to continue breeding. What is the probability that his descendants will be blind again? 2) Determine the genotypes of all individuals participating in the crossing. 3) How many types of gametes does a blind dog produce?

14. When two fruit flies were crossed, out of 98 offspring, 23 turned out to be black, the rest were gray in color. Which trait is dominant? Determine the genotypes of the parental forms.

15. When gray chickens were crossed with black ones, all the offspring were gray in color. In F 2, 96 chickens were obtained. How many F 2 hens, when crossed with roosters of the same genotype, can produce black chickens?

16. Hypophosphatemia (a disease of the skeletal system) is inherited in humans as an autosomal recessive trait. Myopia is determined by a dominant autosomal gene. Both traits are inherited independently. 1) In a family, both parents are heterozygous for the analyzed genes. Determine the probability of having a child suffering from both diseases. How many children (%) in this family are completely homozygous? 2) In the family, the mother and all her relatives are healthy. The father suffers from both diseases. Determine the probability of having healthy children if it is known that only the father suffered from myopia.

17. Aniridia is an autosomal dominant disease characterized by the absence of the iris. 1) What is the probability of having sick children in a family of healthy parents if the wife’s parents and all relatives are healthy, and the husband’s mother suffered from the specified disease? 2) What is the probability of having sick children in a family of healthy parents if both the husband and wife have one of the parents suffering from aniridia? 3) A child with aniridia was born into a family of healthy parents. What is the probability of having a second child healthy?

18. In humans, two forms of hereditary deafness are known, both are inherited as recessive autosomal unlinked traits. 1) determine the probability of having sick children in a family where both parents have the same form of deafness, for which they are heterozygous; 2) determine the probability of having sick children in a family where both parents have various forms of deafness, and for other forms they are homozygous; 3) determine the probability of having sick children in a family where both parents have both forms of deafness, if it is known that the mothers of both spouses suffered from one form of deafness, and the fathers from another.

19. In humans, two forms of fructosuria are known and both are inherited as autosomal recessive unlinked traits. One of the forms is characterized by a rather severe course, and the second by a mild course. A myopic man with a mild form of fructosuria is married to a woman with signs of a severe form. The first child in this family had normal vision, but was sick with a severe form of fructosuria. Determine the probability of having healthy children in this family if the maternal grandmother suffered from a mild form of fructosuria, and the grandfather and all his relatives are healthy.

20. How many types of gametes will be produced by an organism having the following genotype: a) AaBbCs; b) АаВВСс; c) Aavvss; d) aaВвСС.

Related information.

Incredible facts

Researchers have proven that Blue eye color is the result of a genetic mutation that probably occurred between 6,000 and 10,000 years ago. Scientists say they have discovered the reason why some of us have blue pigment in the iris.

Professor Hans Eiberg, leader of the research team at the University of Copenhagen, claims that all humans originally had brown eyes. As a result of a genetic mutation, the color of the eyes has changed, and both of these pigments are present in the iris of the eyes of modern people.

According to experts, most likely blue eye color comes from the countries of the Middle East or the northern part of the Black Sea coast. It was in this area that the largest migration took place during the Neolithic period (about 6,000 – 10,000 years ago). People moved in huge groups to the northern part of Europe.

"These are just our guesses," says Professor Eyberg. According to him, this could also be the territory of the northern part of Afghanistan.

Genetic mutation

This mutation, which occurred thousands of years ago, affected the so-called OCA2 gene and literally, “turned off” the ability of brown eyes to produce dark pigment.

For those less educated on this issue, it is worth explaining that the OCA2 gene is involved in the production of melanin, the pigment that gives color to hair, eyes and skin. A mutation in neighboring genes does not completely immobilize the OCA2 gene, but it certainly limits its action, thereby reducing the production of melanin in the iris. Thus, brown eyes are “diluted” with blue pigment.

If the OCA2 gene were completely turned off, those who inherited this mutation would lose melanin for their skin, hair and iris. Sometimes this happens. We call people with a complete lack of melanin albinos.

Professor Eyberg and his colleagues examined the DNA of blue-eyed people from countries where the majority of the population has brown eyes. Residents of Jordan, India, Denmark and Turkey took part in a number of experimental observations.

The results of Professor Eyberg's research are very important for genetics in general. For the first time in 1996, a scientist suggested that the OCA2 gene is responsible for eye and hair color. From this moment, a very important stage began in the study of the OCA2 gene, as well as all processes in the body associated with this gene.

The results of this study were published in the journal Human Genetics, which clearly indicate that all blue-eyed inhabitants of our planet were once the owners of brown eyes, and only as a result of the mutation that occurred, the pigment of the eyes changed.

Albinism in humans

It is known that the cause of albinism is the absence of the enzyme tyrosinase, which is involved in the normal synthesis of melanin.

There are several main types of this genetic disorder:

1. Oculocutaneous albinism.

2. Temperature-sensitive albinism.

3. Ocular albinism.

Treatment of any of these types is unsuccessful. It is impossible to compensate for the lack of melanin or prevent various visual disorders that are an integral part of the disease.

What happens to a child who is heterozygous for eye color? The answer is: he will have brown eyes.

The fact is that the child has one gene that can form a large amount of tyrosinase, and a gene that can form a small amount of tyrosinase. However, a single gene can produce a relatively large amount of tyrosinase, and this may be enough to turn the eyes brown.

As a result, two parents, one of whom is homozygous for brown eyes and the other homozygous for blue eyes, have children who are heterozygous and at the same time have brown eyes. The gene for blue eyes does not appear.

When a person has two different genes for some physical characteristic at identical locations on a pair of chromosomes and only one gene is expressed, that gene is called dominant. A gene that is not expressed is recessive. In the case of eye color, the gene for brown eyes is dominant to the gene for blue eyes. The gene for blue eyes is recessive to the gene for brown eyes.

It is impossible to tell just by looking at a person whether he is homozygous or heterozygous for brown eyes. Either way, his eyes are brown. One way to say something definitive is to find out something about his parents. If his mother or his father had blue eyes, he must be heterozygous. Another way to know something is to see the color of his children's eyes.

We already know that if a man who is homozygous but has brown eyes marries a woman who is homozygous for brown eyes, they will have children who are homozygous for brown eyes. But what will happen if he marries a heterozygous girl? A homozygous male would only form sperm cells with brown eye genes. His heterozygous wife would produce two types of eggs. During meiosis. since her cells have both a brown eye gene and a blue eye gene, the brown eye gene will travel to one end of the cell and the blue eye gene to the other. Half of the formed eggs will contain the gene for brown eyes, and the other half will contain the gene for blue eyes.

You need to understand that eye color depends not only on the pigment produced. The iris consists of anterior and posterior layers. The color of the eye depends on the distribution of pigments in different layers. In addition, the vessels and fibers of the iris play a role. For example, green eye color is determined by the blue or gray color of the back layer of the iris, and light brown pigment is distributed in the front layer. The total is green.

The definition of gray and blue eyes is similar, only the density of the fibers of the outer layer is even higher and their shade is closer to gray. If the density is not so high, then the color will be gray-blue. The presence of melanin or other substances produces a small yellow or brownish impurity.

The structure of the black iris is similar to the brown one, but the concentration of melanin in it is so high that the light incident on it is almost completely absorbed.

The chance of a sperm cell fertilizing an egg with the gene for brown eyes or an egg with the gene for blue eyes is therefore 50/50. Half of the fertilized eggs will be homozygous for brown eyes, and half will be heterozygous. But all children will have brown eyes.

Now suppose that both father and mother are heterozygous. Both would have brown eyes, but both would also have the gene for blue eyes. The father would form two kinds of sperm cells, one with the gene for blue eyes and one with the gene for brown eyes. In the same way, the mother would form two types of eggs.

Several combinations of sperm and egg cells are now possible. Suppose one of the sperm cells with the brown eye gene fertilizes one of the eggs with the brown eye gene. The child in this case will be homozygous for brown eyes and will naturally have brown eyes. Suppose that a sperm cell with a gene for brown eyes fertilizes an egg cell with a gene for blue eyes, or a sperm cell with a gene for blue eyes fertilizes an egg cell with a gene for brown eyes. In either case, the child will be heterozygous and will still have brown eyes.

But there is another option. What if a sperm cell with the blue eye gene fertilizes an egg with the blue eye gene?

In this case, the child will be homozygous for blue eyes and will have blue eyes.

Thus, two brown-eyed parents can have a blue-eyed child. A gene that had seemed to disappear appeared again.

Besides, you can tell something about the parents by looking at the child. Although their eyes are brown, just like the homozygous person, you know that they both must be heterozygous, otherwise the gene for blue eyes would not express itself.

Chapter from the book " Races and peoples»

William Boyd "Tsentrpoligraf" 2005

Approximate map of the distribution of blue and green eyes in Europe.

Blue And blue eyes are most common among the European population, especially in the Baltics and Northern Europe. Eyes of these shades are also found in the Middle East, for example, in Afghanistan, Lebanon, Iran.

Grey eye color is most common in Eastern and Northern Europe. It is also found in Iran, Afghanistan, Pakistan and parts of Northwest Africa.

Purely green eye color is extremely rare. Its speakers are found in Northern and Central Europe, less often in Southern Europe.

Brown- the most common eye color in the world. It is widespread in Asia, Oceania, Africa, South America and Southern Europe.

Black the type is widespread primarily among the Mongoloid race, in South, Southeast and East Asia.

PSYCHOLOGY

Psychology of sympathy

Appearance is not the only factor on which our attitude towards people depends. When we get to know a person, in addition to his appearance, we immediately notice his other properties that enhance or, conversely, reduce the impression that his appearance made on us.

There are certain prevailing ideas about what a positive person should be. So, many of us are convinced that a girl should be beautiful and a man should be smart. If you look at it, the requirement is quite cruel: clearly, not all girls are beautiful, just as not all men are very smart (after all, when we say “smart,” we mean that he is smarter than others, smarter than the majority, stands out from the majority). It turns out that we are ready to recognize only some privileged part of our fellow citizens as worthy of attention, defining everyone else an order of magnitude lower. In everyday life, of course, we don’t think about it, we don’t analyze this stereotype so deeply, but it lingers in our consciousness, takes root, and it turns out that it’s not always easy to get rid of it.

The next circumstance on which the emergence of sympathy depends is the dissimilarity or similarity of the partners. They often say that these people got together because they are similar to each other. They say it no less often. that people got together precisely because they were very different. Depending on the situation, either one or the other is significant.

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 remains virtually unchanged 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 a complete absence of pigment, the iris is white. 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 is the 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-eyes inhabit mainly the north of Europe, although they are found throughout the world.

Grey

With a high collagen density in the outer layer of the membrane, the iris 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, the eyeballs of black-eyed people 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 to parents with dark and light eyes will inherit a dark (dominant) or medium iris color.

Science, which grew from these observations and generalizations, calculated the heredity of eye color in children as accurately as possible. 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 a brown-eyed child cannot be born to 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 they are 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 of different colors are an almost unique phenomenon, but this is not a pathology. Multi-colored 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 are visible through the transparent membrane, so the eyes become 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. The genetic mutation that resulted in the appearance of the first blue-eyed man appeared 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.