What is kinship marriage dangerous by? This world of
agreed on the sister a wedge we Will leave an era of the imperial houses considering as the law the conclusion of intsestny marriages for maintenance of purity of blood where it and should be. Because rule: “ At all others blood! “ did not guarantee the birth wise, strong in spirit and a body of posterity to either many Egyptian Pharaohs, or Greco`s governors - the Macedonian dynasty, nor leaders of Inca, “ company “ which blue blood sank Into oblivion together with her owners.
If to lay aside ethical, moral and religious reasons and to concentrate only on genetics, then the picture will look so. There is such concept as inbreeding coefficient (English “ crossing of closely related organisms). At the family of the uncle and the niece it makes 1/8, at cousins and sisters 1/16, at three times removed 1/32, at relatives of the fourth knee 1/64 and so on. The eighth and sixty fourth say these that the relationship is farther, the it is less than similar (identical) genes in the genetic device of each relative.
From here it turns out that at kinship marriage the probability of emergence of sick posterity directly depends on degree of relationship of spouses. In due time the geneticist E. L. Dadali wrote about the similar phenomena. He explained it as follows. Among hereditary diseases there are two groups: the first arises under the influence of prepotent genes, and another - under the influence of recessive.
Even in singular the prepotent gene conducts to an illness. It is the mine of the slowed-down action put in a human body. As, for example, at such rare disease, as trochee of Gentington. It appears in the presence of the one and only abnormal gene. The person who inherited him is doomed. The gene begins destruction of an organism when to the carrier 30 - 35 years are executed. Absolutely healthy, it for a short time turns into a wreck: ceases to move, loses memory and the speech. The medicine is only capable to alleviate physical suffering, but to cure not in forces.
The recessive gene, unlike prepotent, can not ruin the carrier, and is quiet wait when he is transferred to the next generation. And here danger of the birth of sick children is covered, especially, if parents are relatives also both are carriers of a recessive gene. Meeting two identical “ harmful “ genes - a certain death of the children born in such marriage. Many serious illnesses are so inherited: albinism, glukhonemot, diseases of nervous system and illness of a metabolism, congenital malformations.
The position of geneticists is clear. But it is not necessary to do you the tragedy of love of cousins and sisters, perhaps. At all the birth of the sick child in such marriage is optional. The child can be absolutely healthy (probability of 25 percent) or to be the carrier of a recessive gene (probability of 50 percent).
If it is valid on the cousin “ light a wedge met “ it is desirable to spend the physician - genetic research. The benefit today such consultations are available “ to the simple people “. Collect as much as possible data about health of close and distant relatives: grandmothers and grandfathers (it is very important to know, than these people as they long lived what they died of were ill), parents, cousin and second cousins and sisters.
Having studied these yielded and having taken results of other researches into account, experts of consultation will make concrete recommendations. And further to solve to you, and only to you.
By the way, in one family not only genes of hereditary diseases, but also a set of the genes defining intellectual features from generation to generation circulate. Stories are known the families exclusively rich with the people presented in sciences, arts. For example, forty six relatives of Bach were professional musicians. And Lev Nikolaevich Tolstoy and Alexander Sergeyevich Pushkin`s great-grandmother were sisters.
Legendary Cleopatra became famous in centuries for both beauty, and mind. The daughter of the brother and the sister, she married the brothers too.
Persons interested to have tall children can take into consideration supervision of the German anthropologist F. Nold. Having conducted examination of several thousand young men, he drew a conclusion: the further from each other there are birthplaces of parents, the growth of the successor is higher.
Those who dreams of child prodigies need to consider: in comparison with 20 - summer at 50 - summer fathers the probability of the birth of talented children increases by 10 times. It cannot be told about age of mother. Such data were shown by the analysis of genealogical many outstanding persons.