How are heredity related? Heredity and development. What is inherited

To understand the patterns of human development means to get an answer to the key question: what factors determine the course and results of this process? Although the word “factor” has already been used above, let us recall that this term denotes a compelling reason formed by the combined influence of several simple reasons (variables). What reasons determine personality development?

It has been established that the process and results of human development are determined by the joint influence of three general factors - heredity, environment and upbringing. The following diagram, borrowed from J. Švantsara, illustrates the relationship between the main factors of development. The base (see Fig. 3) is formed by congenital and inherited predispositions, designated by the general term “heredity”. Congenital and inherited predispositions develop under the influence of the main external influences - environment and upbringing. The interaction of these factors can be either optimal (equilateral triangle), or, when overestimating one or the other external term (vertex C 5 or C 2), inharmonious. It is also possible that the congenital and inherited base is not sufficiently developed by both environment and upbringing (triangle ABC 3). This scheme must simultaneously demonstrate that not a single factor acts independently, that the result of development depends on their coordination.

The natural (biological) in man is what connects him with his ancestors, and through them - with the entire living world, with higher animals in particular. Reflection of the biological is heredity. Heredity refers to the transmission of certain qualities and characteristics from parents to children. The carriers of heredity are genes (translated from Greek “gene” means “giving birth”). Modern science has proven that the properties of an organism are encrypted in a kind of gene code that stores and transmits all information about the properties of the organism. Genetics has deciphered the hereditary program of human development. Facts have been obtained that force us to rethink many established pedagogical principles.

Hereditary programs of human development include deterministic and variable parts, which determine both the general things that make a person human and the special things that make people so different from each other. The deterministic part of the program ensures, first of all, the continuation of the human race, as well as the specific inclinations of a person as a representative of the human race, including the inclinations of speech, upright walking, labor activity, and thinking. External characteristics are passed on from parents to children: body features, constitution, hair, eye and skin color. The combination of various proteins in the body is strictly genetically programmed, blood groups and the Rh factor are determined. Inherited physical characteristics of a person predetermine the visible and invisible differences between people.

Hereditary properties also include features of the nervous system, which determine the character and characteristics of the course of mental processes. Defects and deficiencies in the nervous activity of parents, including pathological ones that cause mental disorders and diseases (for example, schizophrenia), can be transmitted to offspring. Blood diseases (hemophilia), diabetes mellitus, and some endocrine disorders - dwarfism, for example, are hereditary. Alcoholism and drug addiction of parents have a negative impact on the offspring.

The variant part of the program ensures the development of systems that help the human body adapt to changing conditions of its existence. Vast unfilled areas of the legacy program are presented for subsequent additional training. Each person completes this part of the program independently. By this, nature provides man with an exceptional opportunity to realize his human potential through self-development and self-improvement. Thus, the need for education is inherent in man by nature. Hardly programmed hereditary traits are enough for survival for an animal, but not for a person.

The pedagogical aspect of research into the patterns of human development covers the study of three main problems - the inheritance of intellectual, special and moral qualities.

The question of the inheritance of intellectual qualities is extremely important. What do children inherit - ready-made abilities for a certain type of activity or only predispositions, inclinations? Considering abilities as individual psychological characteristics of a person, as conditions for the successful implementation of certain types of activities, teachers distinguish them from inclinations - potential opportunities for the development of abilities. Analysis of the facts accumulated in experimental studies allows us to answer the question posed unambiguously - it is not abilities that are inherited, but only inclinations.

The inclinations inherited by a person are realized or not. It all depends on whether a person will receive the opportunity to transfer hereditary potency into specific abilities that ensure success in a certain type of activity. Whether an individual like Raphael will be able to develop his talent depends on circumstances: living conditions, environment, needs of society, and finally, on the demand for the product of a particular human activity.

The issue of inheritance of abilities for intellectual (cognitive, educational) activity raises especially heated debates. Materialist educators proceed from the fact that all normal people receive from nature high potential opportunities for the development of their mental and cognitive powers and are capable of practically unlimited spiritual development. The existing differences in the types of higher nervous activity change only the course of thought processes, but do not predetermine the quality and level of intellectual activity itself. Prominent geneticist academician N.P. Dubinin believes that for a normal brain there is no genetic basis for variations in intelligence and that the widespread belief that the level of intelligence is passed on from parents to children does not correspond to the results of scientific research.

At the same time, educators around the world recognize that heredity may be unfavorable for the development of intellectual abilities. Negative predispositions are created, for example, by sluggish cells of the cerebral cortex in children of alcoholics, disrupted genetic structures in drug addicts, and some hereditary mental illnesses.

Idealist teachers consider the fact of the existence of intellectual inequality among people to be proven and recognize biological heredity as its root cause. The inclinations for cognitive activity, which predetermine upbringing and educational opportunities, are inherited by people to an unequal extent. From this the conclusion is drawn: human nature cannot be improved; intellectual abilities remain unchanged and constant.

Understanding the process of inheriting intellectual inclinations predetermines practical ways of educating and training people. Modern pedagogy places emphasis not on identifying differences and adapting education to them, but on creating equal conditions for the development of the inclinations that each person has. Most foreign pedagogical systems proceed from the fact that education should follow development; it only helps to mature what is inherent in a person by nature, and therefore should only be adapted to the inclinations and abilities of a person.

There is no particular disagreement between representatives of different pedagogical systems in determining special inclinations. Special inclinations for a specific type of activity are called special. It has been established that children with special inclinations achieve significantly higher results and advance in their chosen field of activity at a rapid pace. When such inclinations are strongly expressed, they manifest themselves at an early age if a person is provided with the necessary conditions. Special inclinations are called musical, artistic, mathematical, linguistic, sports and many others.

The question of the inheritance of moral qualities and psyche is especially important. For a long time, the leading position of Russian pedagogy was the assertion that all mental qualities of an individual are not inherited, but acquired in the process of interaction of the organism with the external environment. It was believed that a person is not born evil or kind, generous or stingy, and especially not a villain or a criminal. Children do not inherit the moral qualities of their parents; human genetic programs do not contain information about social behavior. The soul of a newborn, the ancients said, is a “blank slate” on which life writes its own writings. What a person becomes depends entirely on his environment and upbringing. Deciphering the genetic programs, scientists did not find there any genes for good or evil, nor genes for aggression or obedience, as well as other genes involved in morality.

Then why do many serious scientists adhere to the theory of “inherent evil”? And is the proverb that has come down to us from time immemorial true - the apple doesn’t fall far from the tree? Western pedagogy is dominated by the assertion that human moral qualities are biologically determined. People are born good or evil, honest or deceitful, nature gives a person pugnacity, aggressiveness, cruelty, greed (M. Montessori, K. Lorenz, E. Fromm, A. Micherlik, etc.). The basis for such conclusions is data obtained from the study of human and animal behavior. If science recognizes the presence of instincts and reflexes in animals and people (I.P. Pavlov), and instincts are inherited, then why should their inheritance by people lead to actions different from the actions of animals? This is how a bridge is thrown from animal behavior to human behavior, which in a number of cases is recognized as instinctive, reflexive, based not on higher consciousness, but on the simplest biological reflexes. This issue is very complex, and its solution must be approached with all responsibility. Nevertheless, recently domestic specialists have begun to take an increasingly definite, albeit cautious, position on the genetic determination of social behavior. Academician P.K. Anokhin, N.M. Amosov and other prominent scientists, at first veiledly, and recently openly speak out in favor of the hereditary conditioning of human morality and his social behavior.

Man as a biological species has undergone very minor changes over the entire history of his development known to people. This is another strong proof of the immutability of human nature, the strict genetic regulation of human essence. A change in the human species can only occur when scientists have the means to practically interfere with the gene code. What such attempts entail - good or evil, what they can lead to - is now difficult to imagine.

Do our grandmothers' school grades affect our school success? K. Peters provides interesting data on this matter. He compared school grades across three generations. It turned out that the children's average grades will be lower, the lower the grades of the two parents. Let us present one of the tables of K. Peters.

average rating

Just don’t take this data as a fatal omen. Personality development, fortunately, is determined not only by heredity, but, as we see, it must be taken into account.

III. What qualities are passed on from parents to children?

1. Ways of thinking, features of intellectual activity.

2. Character traits.

3. Type of nervous system, temperament.

4. Abilities for various types of activities.

5. Inclinations that serve as the basis for the development of a person’s individual abilities.

6. Eye color, skin color, blood type, Rh factor.

7. Social experience.

8. Moral qualities.

9. Features of speech, memory, attention.

10. Will, perseverance, determination.

11. Cruelty, greed, aggressiveness.

12. Tendency to commit crimes.

The influence of the environment on personality development

A person becomes a person only in the process of socialization, i.e. communication, interaction with other people. Outside human society, spiritual, social, and mental development cannot occur.

We were born as humans, but did not become

Now we move on to the sad facts. They seem to be specially provided to us by nature to identify the laws of human development. The tale of Mowgli is not an idle fiction from beginning to end. Judging by the facts recorded in the history of human civilization, these events could have a real basis. In ancient legends, many stories have been preserved about people fed and raised by animals. What is true in them and what is fiction is now probably impossible to find out. The founders of Rome, Romulus and Remus, suckled by a she-wolf, Mowgli, raised in a pack of animals, a Lithuanian boy raised in a bear’s den, as E. Condillac told about back in 1754, could well have existed. There are 15 known cases of human cubs being suckled by wolves, 5 by bears, one case by baboons, and at least ten other breeds of monkeys. One child was nursed by a leopard, one by a sheep.

In 1920, in India, Dr. Singh discovered two babies in a wolf's den along with a litter of wolf cubs. These were girls, one of them looked about 7-8 years old, the other about two years old. The youngest girl was named Amala, the eldest - Kamala.

How does a wild animal behave in a city apartment? At first, the children taken from the jungle behaved exactly the same way. They walked and ran only on all fours, and only at night. During the day they slept, huddled in a corner and clinging tightly to each other.

The younger girl soon died without learning anything; the eldest lived for about 10 years.

All these years, Dr. Singh kept a detailed diary of observations of Kamala. She studied with great difficulty. It took two years to teach her to stand. Six years later, Kamala began to walk, but still only ran on all fours. It took four years to learn the first six words. Seven years later, the girl’s vocabulary expanded to 45 words, and after another three years - to a hundred. Language progress did not go further. By this time, Kamala fell in love with the company of people, stopped being afraid of bright light, and learned to eat with her hands and drink from a glass. Having reached about the age of seventeen, Kamala was at the level of development of a four-year-old, if not a three-year-old child.

Instead of comments, let us read into the words of G. Itard: “Appearing on the globe physically weak and not possessing innate ideas, being unable to obey the basic laws of his existence, which determined his dominant position in the Universe, a person can only achieve that exceptional position in society in society.” to which nature itself intended him. If there were no civilization, he would turn out to be one of the most insignificant and unreasonable animals... a person is always only what society makes of him..."

The reality in which human development occurs is called the environment. The formation of personality is influenced by a variety of external conditions, including geographic, social, school, and family. Based on the intensity of contacts, the near and far environments are distinguished. When teachers talk about the influence of the environment, they primarily mean the social and home environment. The first is attributed to the distant environment, and the second to the immediate environment. The concept of social environment includes such general characteristics as the social system, the system of production relations, material living conditions, the nature of production and social processes, and some others. The immediate environment is family, relatives, friends.

What is the influence of the environment on the formation of a person? There is no unity in its assessment among teachers who stand on different methodological platforms. More precisely, the enormous importance of the environment is recognized by educators all over the world. Views do not coincide when assessing the degree of environmental influence. As you know, there is no abstract medium. There is a specific social system, specific living conditions for a person, his family, school, friends. Naturally, a person reaches a higher level of development where the near and distant environment provides him with the most favorable conditions.

The home environment has a huge impact on human development, especially in childhood. The family usually hosts the first years of a person’s life, which are decisive for the formation, development and formation. A child is usually a fairly accurate reflection of the family in which he grows and develops. The family largely determines the range of his interests and needs, views and value orientations. The family also provides conditions, including material ones, for the development of natural inclinations. Moral and social qualities of an individual are also established in the family.

The current family is going through hard times. The number of divorces and single-parent families is growing, and the number of socially disadvantaged children is also growing. The family crisis, according to experts, has become the cause of many negative social phenomena, and above all the root cause of the increase in crime among minors. Teenage crime in Russia has reached alarming proportions. A significant number of offenses in the country are committed by teenagers and young people aged 14-18 years.

Both theoretically and practically, the following question is of interest: what has a greater influence on human development - environment or heredity? Experts' opinions were divided. Adherents of the so-called biogenic (biogenetic) direction in pedagogy certainly give preference to heredity, and the sociogenic (sociogenetic, sociologizing) direction - to the environment. Many researchers have tried to establish exact quantitative proportions of the influence of environment and heredity on human development. Very contradictory results were obtained, reliably indicating only one thing: the share of participation of the studied factors in the development of different people is not the same. The influence of the environment, according to representatives of the sociogenic movement, can reach 90%; The influence of heredity, according to supporters of the biogenic direction, is by no means less significant - 80-90%. Balanced assessments that ignore extremes are more credible. For example, the English psychologist D. Shuttleworth (1935) came to the following conclusion regarding the influence of basic factors on mental development:

64% of the factors of mental development are due to hereditary influences;

16% - to differences in the level of family environment;

3% - on differences in raising children in the same family;

17% - due to mixed factors (interaction of heredity with environment).

Of course, science strives for accuracy; that is its goal. But it is unlikely that even the most scrupulous calculations will fully correspond to reality. Each person develops in his own way, and everyone has their own “share” of the influence of heredity and environment. In what proportions the active causes will be intertwined, and what result their interaction will lead to, also depends on many random factors, the actions of which cannot be taken into account or measured.

Let's think about the sad table

Let's turn to the research materials. Here is a table compiled by the French researcher G. Ley. He traces the influence of social factors on the emergence of mentally retarded children, the number of which continues to increase in our country. The table summarizes the results of a survey of the living conditions of 150 normal and 150 mentally retarded Parisian children.

Factors	Number of cases per 150 normal children	Number of cases per 150 mentally retarded children
Abnormal childbirth Convulsions in childhood Artificial nutrition Appearance of the first tooth no earlier than 8 months Beginning to walk after 24 months First word after 24 months Untidy behavior after 36 months Urinary incontinence at school age Maternal grandfather is an alcoholic Paternal grandfather is an alcoholic Paternal grandmother is an alcoholic Grandmother mother's side is an alcoholic Grandfather or grandmother has tuberculosis
Parents have tuberculosis
Ancestors with nervous or mental illnesses
Ancestors with mental illness interned in a hospital
Ancestors - epileptics
Number of brothers and sisters
Number of deceased brothers and sisters	71 (16%)	352 (36%)
Of these, those who died from seizures and brain diseases	36(51%)	256 (73%)
Father is an unskilled worker
Mother works outside the home
The father was tried and punished
The mother was tried and punished
Number of offenders
How many people are there in one room?	1,33	2,65
How many people have one bed?	1,4	2,41
Family income per person in francs	6,68	2,96

IV. Is it possible to say that a child whose parents were drunkards will definitely share their fate?

1. Absolutely. If a person has unfavorable tendencies, they will develop over time.

2. Whether hereditary inclinations will develop into stable personality traits - this depends on training, education and self-education.

3. In an unfavorable social environment, a child with such inclinations will certainly share the fate of his unfortunate parents.

4. Once in an unfavorable environment, a person with such heredity is more likely to become an alcoholic than a person without aggravating heredity.

5. This doesn't mean anything.

The cells through which the continuity of generations is carried out - specialized sex cells during sexual reproduction and unspecialized (somatic) cells of the body during asexual reproduction - do not carry the very signs and properties of future organisms, but only the makings of their development. These inclinations are genes. A gene is a section of a DNA molecule (or a section of a chromosome) that determines the possibility of developing a separate elementary trait. A DNA molecule consists of two polynucleotide chains twisted around each other into a spiral. The chains are built from a large number of 4 types of monomers - nucleotides, the specificity of which is determined by one of 4 nitrogenous bases. The combination of three adjacent nucleotides in a DNA chain makes up the genetic code. DNA is accurately reproduced during cell division, which ensures the transmission of hereditary characteristics and specific forms of metabolism over a series of generations of cells and organisms.

A gene is a group of adjacent nucleotides that encode one protein that determines one trait. The number of genes is very large: a person has tens of thousands of them. The same gene can influence the development of a number of traits, just as several genes can influence the formation of one trait.

Each species of plants and animals has its own quantitative set of chromosomes. In all organisms of the same species, each gene is located in the same place on a strictly defined chromosome. Each cell of the human body contains 46 chromosomes. Almost all the chromosomes in the set are presented in pairs, each of the 22 pairs includes identical chromosomes of the same size, and the 23rd pair is the sex chromosomes: in women it consists of identical chromosomes XX, and in men - XY. In the halogen set of chromosomes there is only one gene responsible for the development of this trait. The dilloid set of chromosomes (in somatic cells) contains two homologous chromosomes and, accordingly, two genes that determine the development of one particular trait.

Genetic information is encoded in the sequence of nitrogenous bases contained in the DNA molecule. Nitrogenous bases can be considered as “letters” of the genetic alphabet. The sequence of bases forms "words". Genes are a kind of “sentences” written in genetic language. Accordingly, the genetic content of an organism is like a “book” made up of genetic sentences. Unlike the strictly defined arrangement of nitrogenous bases in two complementary parts, there are no restrictions as to the order in which the bases must follow each other along the same chain. Thanks to this, there is a virtually unlimited number of different DNA molecules. The number of possible genetic messages encoded by sufficiently long DNA chains is practically unlimited.

Three evolutionarily fixed universal processes are responsible for the reproduction of hereditary properties in generations of plants, animals and humans:

Reproduction of ordinary (somatic) cells - mitosis - simple division, before which the number of chromosomes in the cell doubles through self-reproduction;

Reproduction of germ cells - meiosis;

Fertilization.

Genes control the development and metabolism of the body. The hereditary transmission of characteristics from parents to offspring is a conservative process, but this conservatism is not absolute, since otherwise evolution would be impossible. The information encoded in the DNA nucleotide sequence is usually exactly reproduced during replication.

Each newborn carries a complex of genes not only from its parents, but also from distant ancestors, i.e. his own, uniquely rich hereditary fund or a hereditarily predetermined biological program, thanks to which his individual qualities arise. This program is naturally and harmoniously implemented if:

Biological processes are based on fairly high-quality hereditary factors;

The external environment provides the growing organism with everything necessary for the implementation of the hereditary principle. Skills and properties acquired in life are not inherited, however, every born child has a huge arsenal of inclinations, the development of which depends on:

Conditions of education and training;

Social structure of society;

Parents' care and effort;

The wishes of the child himself.

The external environment for a child is, first of all, the conditions created by his parents or the people around him, various climatic, geophysical and other factors, the impact of which can significantly change the nature of hereditary information. And it can be realized partially or completely.

The pedagogical aspect of research into the patterns of human development covers the study of three main problems - the inheritance of intellectual, special and moral qualities.

Perhaps everyone has ever heard such phrases: “just like your father,” “an apple from an apple tree...”, “she looks like her mother.” All this suggests that people note family similarities. Human heredity is the ability of an organism at the genetic level to transmit its own traits to the future generation. There is no direct and effective influence on this, however, there are certain ways to prevent the development in a person’s character of negative traits received from parents or other ancestors.

What is inherited

According to research, any individual can pass on to his offspring not only any external traits or diseases, but also his attitude towards people, temperament, and abilities in science. The following positive and negative characteristics of a person are inherited:

Chronic diseases (epilepsy, mental illness, etc.).
Possibility of producing twins.
Alcoholism.
Tendency to break laws and
Suicidal tendencies.
Appearance (eye color, nose shape, etc.).
Talent for any creativity or craft.
Temperament
Facial expressions, voice timbre.
Phobias and fears.

This list shows only some of the traits that are inherited. Do not despair if one of the negative characteristics occurs in you or your parents; it is not at all necessary that it will be fully revealed in you.

Is it possible to influence heredity by determining that a person has a predisposition to breaking the law? According to psychological and sociological research, a negative situation can only be prevented if certain conditions are met.

Influence of genes

Genetics has proven that a person exactly adopts the preferences and fears of his parent. Already during the formation of the fetus, a certain laying occurs, which will subsequently make itself felt, manifesting itself under the influence of any factors.

Is it possible to influence heredity? Social science, like other sciences about society and man, agree on one thing here: yes, it is not only possible, but also necessary to influence it. Despite the fact that an individual's genes and behavioral characteristics are closely interrelated, heredity does not predetermine his future. For example, if the father is a thief or a murderer, then it is not at all necessary that the child will become one. Although the likelihood of such a development of events is still high, and the descendant of a criminal is more likely to end up behind bars than a child from a prosperous family, this may still not happen.

Many parents, having discovered an alcoholic or a criminal in the family tree, wonder whether it is possible to influence heredity. It is impossible to answer this question briefly, since there are various factors that aggravate the development of hereditary predispositions. The main thing is to promptly detect negative characteristics that are inherited and prevent their further development, protecting the child from temptations and nervous breakdowns.

Heredity and character traits

With help, parents pass on to their children not only a predisposition to certain negative life situations, but also character and temperament. For the most part, the manner of communicating with others has “natural” roots - heredity. Genetic behavior is more often used by children and adolescents due to their not fully formed character.

The further development of a person’s character traits and behavioral characteristics is influenced by temperament, which is transmitted only by inheritance. It cannot be acquired or developed; it consists of the traits of the mother or father (grandfather, grandmother, uncle and others) or from a mixture of several characteristics of the parents’ behavior. It is the temperament that determines how a child will behave in the future, as well as what place he will occupy in society.

Is it possible to influence heredity? (5th grade, social studies). Answer to the question

You can often find statements that heredity can be influenced by direct intervention in human genes. However, science is not yet developed enough to influence the body at this level. Heredity can be influenced through the educational process, training, psychological training, as well as through the influence of society and family on a person.

Factors influencing the inheritance of behavior

In addition to genetic transmission, there are other ways to copy parental traits in a child's behavior. There are factors and certain conditions under which children begin to adopt and inherit behavior and attitudes to life from adults:

Family. The way parents treat each other and how they treat the child penetrates deeply into his “subcortex” and is consolidated there as a normal model of behavior.
Friends and relatives. Children's attitude towards strangers also does not go unnoticed - they adopt the behavioral characteristics of their parents and subsequently communicate with others in this way.
Life, living conditions.
Material security (poverty, prosperity, average standard of living).
Number of family members. This factor has a greater impact on the future of the child, on who he chooses to start a family.

Children completely copy their parents, but is it possible to influence heredity in this case? Yes, but it completely depends on the parents. For example, if a father constantly drinks and beats his wife, then in the future the son will be prone to cruelty towards women, as well as alcoholism. But if love and mutual assistance reign in the family, then the effect will be exactly the opposite of the previous example. It is worth remembering that boys copy their fathers, and girls copy the behavior of their mothers.

Is it possible to influence heredity and why is it worth doing?

The genetic predisposition to dangerous diseases itself cannot be eliminated, but the likelihood of developing the disease can be significantly reduced. To do this, you need to lead a healthy lifestyle, not overexert yourself, and exercise in moderation. It is imperative to try to influence heredity, as this will allow you to remain healthy for a long time.

Is it possible to influence heredity by trying not to give in to temptations? This option is convenient, but only until the moment a person loses self-control due to a nervous breakdown or other negative situation (psychological shock, for example). It is necessary to influence heredity not only through control over your weaknesses, but also through your social circle. After all, a teetotaler will never drink unless there is a reason for it: a marginal close circle or a tragedy that has shaken him.

Heredity is the ability of organisms to transmit their characteristics and developmental characteristics to their offspring. Thanks to this ability, all living beings retain the characteristic features of the species in their descendants. This continuity of hereditary properties is ensured by the transfer of genetic information. In eukaryotes, the material units of heredity are genes localized in the chromosomes of the nucleus and the DNA of organelles. Heredity, along with variability, ensures the constancy and diversity of life forms and underlies the evolution of living nature. Heredity and variability are the subject of genetics.

Of all organic molecules, only nucleic acids have the ability to self-reproduce. Meanwhile, being in cells, they control their structure and properties (activity). Therefore, the uniqueness of life in the genetic sense lies in the fact that nucleic acids, through germ cells, provide a chemical connection between generations. Thanks to reproduction, heredity and variability, the life of species continues indefinitely as a continuous alternation of generations with the preservation of chemical connections between them.

The uniqueness of life is also determined by the constancy of species. In the process of reproduction, the original organisms always produce themselves, i.e. “like gives birth to like.” The offspring of a pair of mice are always mice, just as two bacterial cells are bacteria of the same species as their parent cell. Consequently, the constancy of species is determined by the transfer of similarities from parents to offspring, that is, by the inheritance of the properties of their parents, as a result of which organisms of all generations (generations) within a species are characterized by common hereditary (genetic) behavior.

Heredity is the transmission of similarities from parents to offspring or the tendency of organisms to resemble their parents. Heredity means the transfer of anatomical, physiological and other properties and characteristics from organisms of one generation (generation) to organisms of others. Since the connection between generations is ensured by germ cells, and fertilization is the fusion of the nuclei of these cells and the formation of a zygote, the nuclei of the germ cells form the physical basis of such a connection. When it comes to the heredity of organisms, it should be understood that the only material that is inherited by offspring from their parents is genetic material concentrated in nuclear structures (chromosomes) and representing genes (units of heredity). Consequently, the offspring inherits from their parents not traits (properties), but genes that control these traits (properties), and the indicator of the genetic determinacy of traits is the heritability of the latter.

A distinction is made between inheritance that is not linked to gender and inheritance that is controlled, limited and linked to gender. Sex-neutral inheritance refers to inheritance that does not depend on the sex of parent or offspring organisms. In sex-controlled inheritance, genes are expressed in both sexes, but in different ways. Sex-limited inheritance is when genes are expressed in only one sex. Finally, sex-linked inheritance is determined by the localization of the corresponding genes on the sex chromosomes. In addition to these types of inheritance, polygenic inheritance is also distinguished, when the heritability of a trait is subject to control by several genes.

However, organisms that are descended from any given pair of parents are not all exactly the same. In the same litter of mice or in the same culture of bacteria (derived from the same bacterial cell), you can find organisms that differ from their parents in some way. Sometimes the offspring exhibit characteristics that were characteristic only of distant ancestors, or characteristics that are completely new not only to their parents, but also to their distant ancestors. Consequently, individual organisms are characterized by differences and variability of characteristics.

The opposite property of heredity is variability. It consists of changes in genetic material accompanied by changes in the characteristics of the organism. The result of variability is the formation of new variants of organisms, the continuity of the diversity of life.