In modern genetics, crossing closely related individuals is called inbreeding. The higher the inbreeding coefficient, the greater the chance that recessive genes for hereditary diseases will occur. So for an uncle and niece it is 1/8, for a cousin - 1/16, for second cousins - 1/32, for fourth cousins - 1/64.
Even if the degree of relatedness is greater, the inbreeding coefficient will still be sufficient for a child in a pair of distant relatives to die in the womb or be born mentally retarded or physically underdeveloped. This percentage ratio and the pattern associated with it were described by Elena Leonidovna Dadali, a geneticist of the highest category, professor and author of many scientific works on genetics.
Distant kinship is also dangerous because the spouses may not even be aware of their blood ties and the presence of an unwanted recessive gene. The birth of a sick child then becomes a complete surprise and a very painful blow to the well-being of the couple. When people marry who do not have any family ties, the percentage of matches of mutant recessive genes is negligible, which is why children are born healthy.
Mutant recessive genes are a very dangerous thing, hidden from prying eyes like a time bomb. They can cause a variety of mutations, ranging from albinism and deafness to such serious illnesses as hemophilia or Tay-Sachs disease. The latter is common in some peoples of the world and is fraught with severe damage to the nervous system. A sick child never lives longer than 4 years.
As is known, representatives of the Russian royal family suffered from hemophilia. But these 2 ailments are only the tiny tip of the iceberg of hereditary diseases that can be caused by the meeting of mutant recessive genes. Only genetic analysis, which is a normal pre-wedding practice in many civilized countries of the world, can prevent it.
You can't order your heart. These words have been around for many years, no one knows who first used them, but they are still relevant today. The issue of consanguineous marriage was hotly debated both 200 years ago and in the modern world. There are always two points of view in any dispute. This question is no exception. Opponents refer to genetic deviations of children from such a marriage and its unnaturalness, while supporters believe that marriages between relatives, in particular cousins, are a completely harmless phenomenon. Let's try to figure out whose point of view is closer to the truth.
History of marriages between cousins
There are countless examples in history when marriages between relatives were actively practiced. Moreover, the motives for such actions were more often political or financial than love. Imperial or royal dynasties did not want to see people with different blood in their ranks. That is why marriages between brothers and sisters, aunts and nephews quite often took place, because there were not so many representatives of royal dynasties and relatives had to be married.
History also knows of cases of marriages between relatives due to family beliefs, in which it was believed that money should not leave the family. But only a small number of nationalities had such motives.
There were other reasons for such unusual marriages. Aristocratic families very much valued their family, their surname, and the arrival of new blood meant almost the collapse of the ideal family. However, in those days a lot of children were born with mental and physical disabilities.
Family ties: a genetic perspective
Modern scientists, conducting various experiments, have determined that it was consanguineous marriages that became the most important reason for the extinction of the dynasty of the Egyptian pharaohs. They also constantly insist that children whose parents are close relatives are more susceptible to various physical abnormalities. A striking example of this is the children of royal dynasties, who were much more likely than others to have various genetic diseases.
Recently, a theory has also emerged about the benefits of mixing blood. The more blood a child has, the stronger his health and significantly better mental abilities.
Modern research
What can be said about the modern world and, for example, an isolated case of related marriage? Many people wonder whether it is possible to marry a cousin or marry a cousin if there have been no such marriages in the family before. In this case, scientists do not see anything bad on the part of science if it is isolated. The calculations below are only suitable for cousins; for siblings the statistics are less rosy.
Recent studies by scientists from the United States have shown quite unexpected figures. They concluded that children born to first cousins had a genetic pathology rate of 1.7%. This figure is only slightly higher than that of ordinary couples. Moreover, the risk of having a child with congenital deformities is much higher in people suffering from alcoholism or those who are over 40 years old.
Expert opinion
University of Massachusetts professor Hamish Spencer said that to date, not a single genetic study has given an affirmative answer that marriages between first cousins pose a great risk to the unborn child. Moreover, it is quite difficult to conduct truly independent and correct research.
The thing is that consanguineous marriages in the civilized world are rather an exception to the generally accepted rules. More than 80% of these babies are born in third world countries. There, consanguineous marriages are quite common. In these disadvantaged countries, the percentage of children with physical disabilities is much higher than in other countries. Therefore, it is almost impossible to give an unambiguous answer as to why the baby is not like everyone else (due to the environment, poor nutrition, poor quality medicine, or close relationships).
Is marriage possible from a legal point of view?
The family law of the Russian Federation clearly establishes cases in which a marriage cannot be registered by law. Close relatives - who are they? Article 14 of the Family Code provides a detailed answer to this question. It says that close relatives cannot become husband and wife. These are brothers and sisters (half and full), relatives in descending and ascending lines, namely: children and parents, grandparents and grandchildren. They are the ones who cannot, according to the laws of the country. But first cousins are not close, so the marriage of first cousins is officially allowed.
Russia is not a unique country in this regard; throughout Europe there is also the opportunity to officially legitimize their relations in this case. Consanguineous marriages are prohibited only in some Asian countries and the United States, but not in all states.
Possibility of getting married in an Orthodox Church
Many couples also often wonder if it is possible to marry a cousin and conduct a wedding ceremony. On the one hand, the Holy Scripture states that marriages of only close relatives are prohibited; first and second cousins are not included in them. However, it turned out that a large number of newborns suffered due to consanguineous marriages. Therefore, it is almost impossible to get married in the Orthodox Church. This is a very problematic situation, where it is difficult to give a definite answer; it is recommended to find out about the wedding directly from the priests in a particular temple.
In most cases, couples in love are denied a wedding. Also denied are half-brothers and sisters, uncles and nieces, aunts and their nephews. In addition to blood kinship, the church does not marry those who have spiritual kinship. That is, the child’s godparents cannot be married. However, on this issue there is a difference of opinion among the clergy. Therefore, it is likely that a certain church will agree to perform this ceremony. Parents and their adopted children are also subject to the wedding ban.
Consequences of marriage between cousins
In addition to religious condemnations and medical indications, lovers face a negative attitude towards such a marriage from other relatives. In the countries of the former USSR, such connections were not practiced at all, so this is alien to the average person. Very often, a couple receives a large portion of criticism from people close to them; sometimes family drama can reach a critical situation.
Modern medicine is capable of many miracles, and in this case it can also help the future family. There is a special genetic examination that can determine the risks of possible abnormalities of a child born in a consanguineous marriage. Such studies can determine with great accuracy whether it is medically safe to marry a cousin.
In the process of examining potential parents, doctors thoroughly examine the diseases of previous generations. Genetics also determine how strong the relationship between husband and wife is. After carrying out fairly complex diagnostic procedures, doctors determine how high the percentage of children with serious genetic abnormalities is.
Summing up
So, to sum up the question of whether it is possible to marry a cousin, we can say the following. Only close relatives cannot marry each other. We have already found out who this is according to the law. Cousins and brothers are not close relatives. Therefore, they can link their relationship officially. From a medical point of view, the risk of having children in such a marriage with physical and mental disabilities is slightly higher than that of ordinary couples, but this percentage is not critical.
According to the Holy Scriptures, marriage with a cousin is not prohibited in Russia, but historically it has happened that the church is very reluctant to marry such couples.
Putting all the facts together, we can say that marriage between cousins is a very personal matter. However, there are no serious reasons preventing this. Most of the problems are expected precisely because of the local mentality, since the overwhelming majority of citizens of Russia and other CIS countries have an extremely negative attitude towards the registration of this type of marriage.
Marriages between relatives are not approved by religion and science. This is explained by the fact that there is a very high risk of having defective children.
Despite this, history contains many facts of marriages between relatives. They were not always concluded out of love and consent. There were financial and geopolitical reasons for this.
Marriages between relatives is an issue that does not lose its relevance in the modern world.
In medicine, marriages between relatives are called inbred, which means a union between persons of the opposite sex who have at least one common ancestor.
Often there is such a term as incest - the entry into intimate relations of close relatives, mixing of blood.
History describes tribes in which, in order to preserve the purity of the family, it was customary to marry relatives. As a result, they have almost all disappeared or are on the verge of extinction.
Nowadays, in many countries of the world, marriages between blood relatives based on a certain degree of relationship are not only condemned, but also prohibited by law and equated to a criminal offense. This is explained by physical and moral considerations.
In Russian legislation, there is Article 14 of the Family Code, which does not allow marriage between persons who are related in an ascending or descending line:
- parents and children;
- grandparents and grandchildren;
- brothers and sisters;
- adoptive parents and adopted children.
Despite this, the registry office does not require documentary confirmation or refutation of family ties. Marriage between relatives of the adoptive parent and adopted children is permitted.
In addition, Russian laws do not prevent the creation of a family between:
- uncle and niece;
- aunt and nephew;
- cousins.
This is condemned by society, but is not formally prohibited, which means you can marry such relatives.
At the insistence of genetic scientists, marriages between blood relatives are prohibited at the legislative level.
The Family Code of the Russian Federation also does not allow marriage between blood relatives, under any circumstances.
In this case, the basis for registering a marriage is not even the woman’s pregnancy.
In fact, marriages between relatives can be registered. After all, when submitting an application to the registry office, newlyweds are not required to confirm or deny the existing relationship.
If a couple hides the fact of their relationship, the marriage will be registered, but then it may be declared invalid.
Marriages between adoptive parents and adopted children are only allowed if the adoption is cancelled.
Marriage between closest relatives is considered incest.. But it is worth considering what genetics says about marriage between a second cousin.
Such family ties are considered distant. Marriages between them are possible and quite common, especially in Muslim countries.
The risk of having a child with anomalies from such a union is quite low. There are chances that a full-fledged baby will be born.
The problem with consanguineous marriage is the possibility of spouses carrying mutagenic genes in a latent state.
It is almost impossible to determine which genes these are. It is also unrealistic to predict exactly what abnormalities may appear in a child.
The risk increases that a woman will not be able to bear the fetus, as well as its fading. Therefore, it is difficult to determine how pregnancy will proceed in a related marriage.
A blood test for HLA antigens helps to assess the genetic similarity of spouses.
During pregnancy, specific diagnostics regarding consanguineous marriage are not carried out.
In 2019, a standard ultrasound and a triple test are performed to exclude gross anomalies of fetal development.
For decades, there has been an opinion that the closer the parents are by blood, the more negative the consequences of having children in a consanguineous marriage will be, so they are not desirable.
We are talking about serious vices:
- hemophilia;
- Down syndrome;
- dementia and other pathologies of the nervous system.
Offspring from consanguineous marriages may be mentally and physically weaker.
In an ordinary marriage, the probability of having children with genetic defects and mental retardation is 4%.
In a closely related marriage, the risk increases 5 times.
Science has long proven that intimate relationships between relatives are dangerous to the health of their offspring. Children born from direct relatives can suffer from a number of the most dangerous diseases.
Marriage between first cousins is not considered a consanguineous relationship..
But according to genetics, in such a marriage, compared to unrelated ones, the following increases:
- The risk of stillbirth or intrauterine fetal death is 24%.
- The risk of a child dying at an early age is 34%.
- The risk of developing fetal deformities is 48%.
In addition, geneticists have identified a stable pattern in the frequency of diseases, congenital deformities, mental and physical disabilities in children born as a result of consanguineous marriages.
This point of view on this issue is shared by experts in many countries.
When studying hereditary diseases, much attention is paid to consanguineous marriages. In the case where the parents have at least one common ancestor.
Incest plays an important role in the study of rare blood diseases.
As for marriages between relatives, most often disputes arise specifically over marriages between cousins.
Everything is explained very simply - marriages between persons of the first degree of kinship are prohibited, almost everyone agrees with this. Marriages between distant relatives are not prohibited and do not cause special condemnation.
But marriages between cousins cause a lot of disagreement between scientists, doctors, church ministers and between relatives of those who want to enter into such a union.
Marriages between cousins were for a long time under a moral prohibition. And in many states of America they are outlawed.
But the theory of genetic incompatibility, which became the basis of such beliefs, does not find scientific evidence.
In the modern world, the scientific community is fighting for the right of everyone to register a marriage with a loved one.
Cousins can marry; this is not legally prohibited.
British researchers have come to the conclusion that all laws that prohibit such marriages are a legitimate form of genetic and sexual discrimination.
Researchers have spent a long time studying modern statistics and historical data and have come to the unequivocal conclusion that children born in marriage between first cousins have the same chances of birth defects and genetic diseases as any other babies.
Scientists attribute the ban on such families to social rather than genetic factors.
The likelihood of developing hereditary diseases in marriages of first cousins is approximately 2% higher than in marriages of non-relatives. If you have common ancestors, the risk of carrying the altered gene increases.
If both parents have such a gene, then together with a healthy gene, the chance of the diseased gene appearing is 25%. When two altered genes are found in a couple, the risk that the children in such a marriage will have anomalies is 50%.
The accuracy of the forecast depends on how complete the information about the pedigrees is. It is important to have data on the number of relatives, hereditary diseases and the development of defects in them.
But in any case, without a genetic examination, medical professionals do not advise cousins to think about having children together.
The problem of marriage between cousins affects moral, spiritual and physiological aspects. Each person has the right to make his own choice and no one has the right to influence him.
Starting a family is one of the main stages in the life of mankind. In Russia, as in all civilized countries, marriage between close relatives is considered illegal.
Article 14 of the Family Code of the Russian Federation outlines a direct prohibition on marriage between persons who are closely related.
But there are no legal obstacles to creating families between brothers and sisters who do not have common parents - first and second cousins. Therefore, marriage between such relatives is possible.
It has long been known that marriages between close relatives are fraught with poor heredity.
This opinion emerged based on life practice.
A large number of noble families died out in ancient times because they did not avoid incest.
Religion and science do not approve of such things at all.
Simply because there is a high risk of children being born still or with major abnormalities. People will degenerate.
That is why in our country there is a law that does not allow close relatives of the first generation to register relationships. But, the restriction does not apply to marriage between cousins. This is due to a lower likelihood of the occurrence of pathologies and their offspring.
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What the law says
In ancient times, it was customary to tie bonds only with relatives, for the purity of the family.
Back then people didn’t think about genetics.
Currently, registering relationships between first-degree relatives is prohibited and in some countries is even considered a crime.
In our country, on the basis of Art. 14 IC you cannot enter into marriage relations with close people:
- mother, father and their offspring
- grandparents and grandchildren
- siblings
- adoptive parents and adopted children
But, employees of the civil registry office do not require additional evidence indicating the absence of relationship.
Important! Marriage between adoptive parents and adopted children is allowed in case of cancellation of official adoption.
As for more distant relatives, the law does not impose restrictions on them. This includes first and second cousins. And also uncles and aunts. In general, representatives of a more distant relationship than the first generation.
Marriages between cousins are permitted by Russian law, but citizens react negatively to such marriages.
Even temporary registration between first-degree family members is unacceptable. Even a pregnant woman cannot sign with a relative. Although, in essence, what is the point of this?
However, if you rely on practice, in fact such a marriage can be concluded. Because the law does not oblige civil registry office employees to confirm or deny the presence of family ties. When a couple is silent about the existence of such connections, they will be signed, but if this fact is clarified, the marriage will be declared legally invalid.
Important! In Russia, importance is attached only to officially registered relationships.
It's no secret that everyone has the opportunity to simply live in civilian clothes. When people strongly desire to be together, the lack of official registration will not hinder them. But there is another side to the issue and this is genetics.
For decades now, people have understood that intimate relationships between family members can result in children with various types of disabilities.
This is due to the high probability of encountering the same gene in their offspring.
This will not affect a woman or a man.
But children born by them will most likely have serious pathologies.
Therefore, in such relationships, in addition to condemnation, you can also encounter great unpleasantness. Sometimes cousins come to the decision to build a social unit. When taking this step, it is better to play it safe and undergo a medical examination.
The doctor finds out the percentage of hereditary diseases, establishes the degree of relationship, as well as the likelihood of the birth of sick offspring. In most cases, pathologies do not occur in distant relatives.
If we take into account close relationships, then here are the following percentages of the occurrence of pathologies:
- the probability of a stillborn baby being born is 24%
- death of a child at an early age - 34%
- risk of deformity - 48%
Before building a relationship with a relative, you should think about the risk of giving birth to patients. The law does not establish a restriction on the registration of relationships between cousins, since such relationships carry less risk for offspring.
Results of the latest scientific research
Modern scientists have ceased to be critical of marriage between cousins.
This is due to the results of recent studies.
Of course, there is a percentage of pathologies, but it is very small. However, before entering into such a relationship, scientists recommend conducting a genetic test.
This will help avoid consequences, that is, the birth of defective children. Such relationships affect many aspects, mainly social.
However, how can you judge people who made their own decisions? No one has the right to insist otherwise. It is enough to simply mention the possibility of pathology.
According to scientific research, the risk of having a handicapped child from cousins is only 1.7% greater than when a baby is born in an ordinary family.
In fact, the risk of having children for other categories of people is much higher than this. For example, the birth of a baby in a family of alcoholics or women over 40 years old. Although such marriages are not controlled.
It turns out, from a scientific point of view, marriage between cousins does not have global consequences. Only a small percentage of such families can produce children with pathologies.
In life there are many people born from cousins:
- Alexander Sergeevich Pushkin, for example, was born from the relationship of his uncle and second cousin.
- The no less famous Charles Darwin had a cousin wife. They had ten children. True, three died while still young, but many of those who remained achieved great success in society.
- What can we say about Cleopatra? She was the daughter of her brother and sister. Egyptian traditions did not prohibit such marriages; on the contrary, they did not welcome incest. The queen herself was a true beauty and more than once married her relatives.
- Rudy Julian transformed New York into a metropolis. Before Julian became mayor, he represented the prosecution in court. Not without his participation, gangster John Gott spent the rest of his life. Julian married his cousin, although they divorced after 14 years.
- In the eighties, Greta Skaki was a sex symbol. Her cousin Carlo could not resist her either. This is a completely normal family. They had a son. Their relationship caused a real stir, which is why Greta's career ended.
- Everyone knows Einstein, who is simply a genius. He developed a huge number of physical theories and earned a Nobel Prize. His wife was his second cousin Elsa.
- The famous former president of Iraq had many wives, one of which was his cousin.
- One of the famous bandits of the Wild West, Jesse James, had a cousin as his wife. Their family had two completely healthy children.
Despite the fact that the percentage of defective children between cousins is low, the United States has banned such marriages. This has greatly impacted abortion statistics. Scientists are not sure that this discrimination will end soon, but it is unlikely that anything will prevent people from living together if they want it themselves.
Scientists have proven that children born from relationships between cousins have almost equal chances of developing pathologies, like any other babies.
First of all, countries that ban such marriages pursue social goals rather than medical ones.
All scientists are confident that such laws have no basis. Simply because the probability of an unhealthy offspring appearing in such families exceeds the standard situation by only 2%.
But no one takes into account that parents can be people over forty years old. In addition, this deviation includes drug addicts and alcoholics. And, as you know, they are more likely to give birth to a sick person.
One of the most important stages in life is the creation of a separate unit of society. All civilized countries have introduced restrictions on the registration of relations between family members belonging to the first generation. Russia is no exception.
In the video you can see what will happen if a brother and sister have children:
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In the occurrence of hereditary diseases, great importance is attached to consanguineous marriages, that is, to such marriage unions when spouses have one or more common ancestors.
It has long been noted that children from these marriages will be born weaker, which is manifested in increased morbidity and mortality. Moreover, the closer the degree of relationship between the parents, the more pronounced the adverse consequences. The role of consanguinity is especially obvious when studying the pedigrees of children with relatively rare hereditary diseases. Thus, the frequency of marriages between cousins in Europe and North America averages 1%, and their frequency in diseases such as albinism and ichthyosis can reach 18-53%.
The frequency of consanguineous marriages varies among the populations of different countries and regions. Thus, according to American geneticist Kurt Stern, in Brazil, the Netherlands, Sweden and the United States, the frequency of marriages between cousins is relatively low and ranges from 0.4 to 0.05%. However, in a number of other countries it is still very high. For example, in India in cities it is 12.9% and in rural areas - 33.3%, in Japan - 5.03 and 16.4%, respectively.
It is known that the conclusion of consanguineous marriages is usually facilitated by economic, everyday, legal, religious, geographical, historical, etc. factors.
People have long realized the harm of consanguineous marriages, and even in ancient times there were prohibition laws. At present, in most countries and areas of the world, custom or law directly or indirectly prohibits marriage between relatives.
What is the danger of consanguineous marriages for the health of the offspring? The correct answer can be obtained by turning to genetics. It is believed that every person is a carrier of some pathological genes, i.e., in the language of geneticists, each of us, being healthy, is a heterozygous carrier of certain harmful genes. Among relatives of the same family there are many identical genes, i.e. they (although healthy) are heterozygous carriers of the same pathological gene, and therefore, during a consanguineous marriage, a meeting of two heterozygotes of the same type can occur and the birth of a child - a homozygote.
Thus, consanguineous marriages are dangerous because they sharply increase the risk of a union between two carriers of the same disease.
History shows that in some social groups, consanguineous marriages have been encouraged for centuries. Thus, the ancient Egyptians and Incas in the ruling dynasties, avoiding the “clogging” of royal blood, encouraged marriages between siblings.
It was believed that consanguineous marriages were even useful, that they could, as it were, summarize the favorable characteristics of ancestors. It is known that in some cases, inbreeding (consanguineous marriages) leads to the birth of outstanding personalities. The example usually given is the famous artist Toulouse-Lautrec, who was descended from the marriage of a cousin. The great Russian poet A.S. Pushkin was born from a related marriage.
However, humanity has more extensive information about the dangers of consanguineous marriages for human health. Numerous examples of consanguineous marriages among royal families show their harmful effects on offspring. In 1906, American researcher Adam Woods published a solid book on the inheritance of mental abilities and moral qualities among kings (“Mental and moral heredity in royalty”). He presented an analysis of the family trees of the royal houses of Hanover, Hohenzollern, Condé, Bourbon, Habsburg, and Oldenburg.
It is quite natural that many of the conclusions of an American researcher in our time sound naive. Perhaps, if Woods had had modern knowledge of genetics and medical capabilities at that time, he probably would have been able to identify something common among members of these families, such as metabolic disorders, and thereby explain such frequent disorders of the nervous system. .
In this regard, the reader may be of some interest in the pedigree of the so-called “royal porphyria”, published relatively recently - in 1968. Porphyria is a rare but severe hereditary disease with a recessive type of transmission. The basis of the disease is believed to be an increased formation of alpha-aminolevulinic acid in the body, which is accompanied by increased secretion of a special substance, porphobilinogen, in the urine (port-wine-colored urine). The disease does not manifest itself as constant, but very severe abdominal pain and nervous system disorders. The pedigree of “royal porphyria” shows that this disease was inherited in the Stuart, George (House of Hanover) and Hohenzoller dynasties. It has been suggested that this serious illness can explain some of the insane actions of Mary Stuart, the cruelty of James I and James II, the madness of George III and George IV and other monarchs.
The famous Soviet geneticist V.I. Efroimson explains this susceptibility of royal dynasties to hereditary ailments not only by consanguineous marriages, but also by the lack of natural selection.
Various national, religious, territorial and other isolation factors play a significant role in maintaining a relatively high frequency of consanguineous marriages. In this regard, the study of the health status of the population living in isolates has attracted the attention of geneticists.
Isolates include population groups that, due to various conditions (geographical, religious, social, historical, etc.) lead a separate lifestyle. Due to the small population of these groups, it can be very difficult to find a bride or groom, and marriages take place mainly within this small community. Such isolates are not uncommon; they still exist in many countries around the world. More often they arise in the Far North in the form of small settlements separated from each other by roadless areas or in the south, in mountainous or desert areas.
Currently, as part of an international biological program in many countries, scientists are conducting joint studies of the biological characteristics of different ethnic groups and isolates: in South America, the Middle East, the Hawaiian and Solomon Islands, the Eskimos of Greenland, and Alaska.
Isolates also include various socio-economic or racial strata in populous cities, wherever a group of people, part of a larger population, tends to marry only within their own circle, and this continues for many generations. For example, Jewish communities in England and Germany, Old Believers, Indians in the USA.
As we have already noted, a characteristic property of isolates is a high frequency of consanguineous marriages, or inbreeding. In isolates, the number of carriers of one “harmful” gene can reach more than 60%, and in the presence of frequent consanguineous marriages, the risk of “separation of homozygotes” becomes very high, i.e., the appearance of patients with hereditary defects. These are not theoretical calculations, these are well-known facts.
In Denmark, Sweden, Switzerland, Japan, France and other countries, examination of various isolates made it possible to detect new, previously unknown recessive mutations in humans. It turned out that the population of each isolate is characterized by its own hereditary anomalies.
Thus, genetics shows not only the social harm of caste, sectarianism, and chauvinism, but also their direct threat to human health. Economic progress, improved means of communication, increased welfare and culture, sanitary and hygienic knowledge led to the inevitable breakdown of isolates. The intensified process of migration and urbanization of the population leads to a significant reduction in isolation factors and the frequency of consanguineous marriages. Scientists say that the number of mixed marriages is constantly increasing, and this reduces the incidence of hereditary diseases.
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