The moment of conception determines a person's blood group; it is believed that it is unchanged throughout life. Scientists at the beginning of the twentieth century identified several systems of groups. Two people with the same system do not exist in the world, the only exception is identical twins.
Heredity factors
It happens that the children's blood type does not coincide with the parent's, which raises a lot of questions. This question was opened by a scientist from Australia K. Landsteiner. Studying the behavior of red blood cells in different people, he deduced three AOB systems. In some, red blood cells are evenly distributed, in others, they stick together. Genes with information about the presence or absence of agglutinogens are inherited. This is how I (OO), II (AA or AO) and III (BB or VO) appeared, and the fourth (AB) was discovered a little later. In all compounds, the first letter means information about the presence or absence of agglutinogen, which the child will receive from the mother, the second - from the father.
For example:
- with I (OO) antigens A and B are absent, therefore, if the father and mother have the first group, then the child will inherit it;
- one parent with the first, the other with the second, then the offspring can be born with I or II;
- if the mother has II, and the father has III, or vice versa, then the children will take any of the four;
- I and III - give only the first and third;
- if the parents have a fourth, then the baby will be born with any other than the first, since both agglutinogens are present in the hereditary set. Thus, the child's blood group may well not coincide with the parent's.
There are exceptions to all the rules
Scientists have identified the fact of exclusion, when both parents have IV (AB), and the child is born with I (OO). There are agglutinogens in the blood, but for some reason they do not appear, this phenomenon is still being investigated. This fact is quite rare, even less common in the Caucasian race. The "Bombay phenomenon", as it is called, is more often manifested in dark-skinned people, in Indians.
Blood transfusion can affect the genetic picture, which will not allow you to determine the exact group in a newborn baby. The agglutinogenic composition can be changed by many factors; it is rather difficult to determine this. Therefore, the blood group of parents and children cannot be called 100% interconnected and, moreover, paternity cannot be established by it. Initially, studies for the presence of heredity were not carried out, and they are not being conducted now.
The most common are I and II, they are owned by almost 40% of the world's population. The rarest is considered IV, which only 3-5% of people have.
In addition to the group, the blood is divided into the Rh factor - positive and negative. Which also has its own rules and exceptions. A person with group I and a negative Rh factor is considered a universal donor. Most often in the world it is required for IV transfusion with positive Rh factor.
