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

The fact is that a child has one gene that can form large number tyrosinase, and a gene that can form a small amount of tyrosinase. However, a single gene can form relatively more tyrosinase, and it may be enough to turn your 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 the eye is defined as blue or gray the posterior layer of the iris, and the anterior layer contains light brown pigment. 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 distribution map 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 North West 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 the South, South-East 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 established ideas about what it should be like positive person. 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 We, of course, don’t think about it, don’t analyze this stereotype so deeply, but it lingers in our consciousness, takes root, and it turns out that getting rid of it is not always easy.

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.

To answer the question The gene for brown eyes is considered dominant. Does he always win if the other parent's eyes are not brown? given by the author old-timer the best answer is 3:1, unless I forgot the arithmetic. That is, such parents will have three children with brown eyes, and the fourth with blue eyes. But if the brown-eyed one himself has ancestors with different colors eye, the likelihood that a child will have blue eyes increases MAYBE....

Reply from Alina[guru]
No, not always. Mom's eyes are brown, father's are blue. I have brown ones, my sister has blue ones, and my second sister has green ones. My son's father has brown eyes, that is, both parents have brown eyes, but his son's eye color is green.

Reply from Neurosis[guru]
no, in my opinion this is nonsense... if he doesn’t always win, why is he dominant?

Reply from Accomplice[newbie]
No, no and no! My mom and dad are brown-eyed, and I have blue eyes! My husband has brown ones, and our children have blue ones! Here!

Reply from Alexey 11[guru]
unfortunately this is so

Reply from Larisa Pavlova[guru]
no, not always, my eyes are gray and my husband’s are brown, our daughter’s eyes are gray like mine

Reply from EYES GREEN KNEES BLUE[guru]
In our case, the brown one won))) as you know, I have green eyes))

Reply from Diver[active]
not always but often

Reply from N.[guru]
We went through this at school, there are calculations on the power of probability, open the textbook "General Biology".)

Reply from Yatyana[guru]
I have brown eyes, my husband has blue eyes, but my daughter still has blue eyes like her husband, which means that brown ones do not always dominate

Reply from Olka[newbie]
Not always!! ! The child does not necessarily inherit dominant gene, but can also inherit a recessive one if it was present in previous generations). And we have brown-eyed parents and a blue-eyed daughter))

Reply from Anna Zilina[active]
won against us. My husband has brown eyes, my daughter also has brown eyes.

Reply from Kisa[expert]
Biology textbook for 9th grade. No, not always.

Reply from ~Give me the Crown, Darling~[guru]
not always. my father has brown ones, and my mother has green ones

Reply from MarS[guru]
My wife and I have brown eyes, and my daughter has blue eyes, like her grandfather’s. AND.. . such a paradox. Until I was seven years old, my eyes were blue, and then they suddenly turned brown, that is, they became caried-dominated:.... (my father had blue eyes, my mother had brown eyes).

Reply from Irina I[guru]
Not always.

Reply from Hyperv strat[newbie]
We cannot isolate all alleles. Compared to all common alleles, it wins. But what if there is such a gray-brown-crimson color that its allele is more dominant? It's impossible to say for sure.

Reply from Vita[guru]
not always

Reply from Lyubov Semyonova[guru]
My eyes are green, my husband’s are brown, and my daughter’s are blue.

Reply from [email protected] [guru]
No. I have brown eyes, but our dad has blue eyes and our daughter has blue eyes.

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 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 most rare color Less than 2% of the world's population has a green eye.
• Türkiye has the highest rate percentage 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 coloration 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!

My friends know how much I am interested in the question of the color of my son's eyes.

For those who don’t know, I’ll tell you: Our dad has brown eyes. My eyes are green with pronounced heterochromia (there are brown veins in the eyes, the rim of the eyes is gray, the iris is green. That is, the eyes are three-colored).

Eye color: from grandparents to our grandchildren: how it is transmitted genetically.
Tables for calculating the eye color of an unborn child.

During pregnancy, many parents are eager to find out what eye color their unborn child will have. All answers and tables for calculating eye color are in this article.

Good news for those who want to pass on their exact eye color to their descendants: it is possible.

Recent research in the field of genetics has discovered new data on the genes that are responsible for eye color (previously 2 genes were known that were responsible for eye color, now there are 6). At the same time, genetics today does not have answers to all questions regarding eye color. However, there is a general theory that, even with the latest research, provides a genetic basis for eye color. Let's consider it.

So: every person has at least 2 genes that determine eye color: the HERC2 gene, which is located on human chromosome 15, and the gey gene (also called EYCL 1), which is located on chromosome 19.

Let's look at HERC2 first: humans have two copies of this gene, one from their mother and one from their father. HERC2 can be brown and blue, that is, one person has either 2 brown HERC2 or 2 blue HERC2 or one brown HERC2 and one blue HERC2:

HERC2 gene: 2 copies* Human eye color
Brown and Brown brown
Brown and blue brown
Blue and cyan blue or green

(*In all tables in this article, the dominant gene is written with a capital letter, and the recessive gene is written with a small letter, eye color is written with a small letter).

Where does the owner of two blue HERC2 green eyes come from - is explained below. In the meantime - some data from general theory genetics: brown HERC2 is dominant, and blue is recessive, so a carrier of one brown and one blue HERC2 will have brown eye color. However, a carrier of one brown and one blue HERC2 can pass on both brown and blue HERC2 to their children with a 50x50 probability, that is, the dominance of brown does not in any way affect the transmission of a copy of HERC2 to children.

For example, a wife has eyes brown color, even if they are “hopelessly” brown: that is, she has 2 copies of brown HERC2: all children born with such a woman will be brown-eyed, even if the man has blue or green eyes, since she will pass on to her children one of her two brown genes. But grandchildren can have eyes of any color:

So, for example:

HERC2 from the mother is brown (in the mother, for example, both HERC2 are brown)

HERC2 from father - blue (father, for example, has both HERC2 blue)

The child's HERC2 is one brown and one blue. The eye color of such a child is always brown; at the same time its HERC2 blue color he can pass it on to his children (who can also receive blue HERC2 from their second parent and then have eyes of either blue or green).

Now let's move on to the gey gene: it can be green and blue (blue, gray), each person also has two copies: a person receives one copy from his mother, the second from his father. Green gey is a dominant gene, blue gey is recessive. A person thus has either 2 blue gene gey or 2 green genes gey or one blue and one green gene gay. At the same time, this affects the color of his eyes only if he has blue HERC2 from both parents (if he received brown HERC2 from at least one of his parents, his eyes will always be brown).

So, if a person received blue HERC2 from both parents, depending on the gey gene, his eyes may be the following colors:

Gey gene: 2 copies

Human eye color

Green and Green

Green

Green and blue

Green

blue and blue

Blue

General table for calculating the eye color of a child, brown eye color is indicated by “K”, green eye color is indicated by “Z” and blue eye color is indicated by “G”:

Eye color

Brown

Brown

Brown

Brown

Brown

Brown

Green

Green

Blue

Using this table, we can say with a high degree of probability that the child will have green eyes if both parents have green eyes or one parent has green eyes and the other has blue eyes. You can also say for sure that the child's eyes will be blue if both parents have blue eyes.

If at least one of the parents has brown eyes, their children may have brown, green or blue eyes.

Statistically:

With two brown-eyed parents, the probability that the child will have brown eyes is 75%, green - 18.75% and blue - 6.25%.

If one of the parents is brown-eyed and the other is green-eyed, the probability that the child will have brown eyes is 50%, green - 37.5%, blue - 12.5%.

If one of the parents is brown-eyed and the other is blue-eyed, the probability that the child will have brown eyes is 50%, blue - 50%, green - 0%.

Thus, if a child’s eyes are not the same color as his parents, there are genetic reasons and justifications for this, because “nothing disappears without a trace and nothing comes out of nowhere.”

In humans, the gene for brown eyes is dominant over the gene causing blue eyes. A blue-eyed man, one of whose parents had brown eyes,

married a brown-eyed woman whose father had brown eyes and whose mother had blue eyes. What kind of offspring can be expected from this marriage?

In humans, the gene for brown eyes dominates the gene causing blue eyes. A blue-eyed man, one of the parents who had brown eyes, got married

on a brown-eyed woman whose father had brown eyes and his mother had blue eyes. What kind of offspring can be expected from this marriage?

No. 2. What kind of offspring can you expect?

from crossing a cow and a bull,
heterozygous for coat color?
Problem No. 3. Guinea pigs have frizzy hair
wool is determined by a dominant gene, and
smooth - recessive.
1. Crossing two curled pigs between
produced 39 individuals with shaggy fur and
11 smooth-haired animals. How many among
individuals having a dominant phenotype,
must be homozygous for this
sign?
2. Guinea pig with shaggy fur
crossed with an individual having a smooth
wool, gave birth to 28 frizzy and 26
smooth-haired offspring. Define
genotypes of parents and offspring.
Task No. 4. An offspring was obtained at the fur farm
in 225 minks. Of these, 167 animals have
brown fur and 58 bluish-gray minks
coloring. Determine the genotypes of the original
forms, if it is known that the gene is brown
coloring dominates the gene,
defining bluish-gray color
wool
Problem No. 5. A person has a gene for brown eyes
dominates the gene causing
Blue eyes. Blue-eyed man, one
of whose parents had brown eyes,
married a brown-eyed woman who
the father had brown eyes, and the mother had blue eyes.
What kind of offspring can be expected from this
marriage?
Problem No. 6. Albinism is inherited in
human as a recessive trait. In the family
where one of the spouses is an albino, and the other has
pigmented hair, have two children.
One child is albino, the other is
dyed hair. What is the probability
birth of the next albino child?
Problems on di- and polyhybrid crossing
Problem No. 8. At a large cattle gene
polledness dominates the horned gene, and
gene for black coat color - above the gene
red color. Both pairs of genes are located
in different pairs of chromosomes.
1. What will the calves turn out to be like if they are crossed?
heterozygous for both pairs
signs of a bull and a cow?
2. What kind of offspring should be expected from
crossing a black polled bull,
heterozygous for both pairs of traits,
with a red horned cow?
Problem No. 9. Dogs have black fur
dominates the coffee, and the short coat
- over the long one. Both pairs of genes are in
different chromosomes.
1. What percentage of black shorthairs
puppies can be expected from crossing two
individuals heterozygous for both traits?
2. The hunter bought a black dog with a short
wool and wants to be sure that it is not
carries genes long hair coffee color.
Which partner according to phenotype and genotype do you need?
select for crossing to check
genotype of the purchased dog?
Problem No. 10. A person has a gene for brown eyes
dominates the gene that determines
development of blue eye color, and the gene
conditioning the ability to better master
right hand, predominates over the gene,
determining the development of left-handedness. Both
pairs of genes are located in different
chromosomes. What kind of children can be if
Are their parents heterozygous?