The moment of conception defines a blood type of the person, it is considered that it is invariable throughout all life. Scientists at the beginning of the XX century defined several systems of groups. Two people with an identical system do not exist in the world, the exception is made only by monoovular twins.
Happens, the children's blood type does not coincide with parental that raises the mass of questions. The scientist from Australia K. Landshteyner opened this question. Studying behavior of red blood cells at different people, it removed three AOV systems. At some – erythrocytes are distributed evenly, at others – stick together. Genes with information on existence or lack of agglyutinogen are descended. So there were I (OO), II (AA or the joint-stock company) and III (BB or BO), and fourth (AV) were opened a little later. In all connections the first letter means information on existence or lack of an agglyutinogen which the child will receive from mother, the second – from the father.
- at I (OO) there are no antigens A and B, therefore, if dad and mom have the first group, then the child will inherit it; - one parent with the first, another with the second, that posterity can be born with I or II; - if, and at the father of III or on the contrary, then children take any of four from mom of II; - I and III– give only the first and third; - if parents have I quarter, then the kid will be born with any, except the first as at hereditary set there are both agglyutinogen. Thus, the blood type of the child can quite not coincide with parental.
From all rules there are exceptions
Scientists elicited the exception fact when at both parents of IV (AV), and the child is born with I (OO). As a part of blood of an agglyutinogena is, but for some reason are not shown, this phenomenon is investigated still. Such fact quite seldom meets, is even more rare at Caucasian race. "The Bombay phenomenon", so it is called, is more often shown at black people, at Indians. Blood transfusion can affect a genetic picture that will not allow to define exact group at the newborn baby. The Agglyutinogenny structure can be changed by many factors, define it quite difficult. Therefore it is impossible to call a blood type of parents and children interconnected for 100% and, especially, to establish paternity on it. Initially researches on existence of heredity were not conducted, not conducted and now. I and II are considered as the most widespread, own them nearly 40% of the population of Earth. It is considered the most rare IV which only 3-5% of people have. Besides group, blood is divided into a Rhesus factor - positive and negative. What also has the rules and exceptions. The person with the I group and a negative Rhesus factor is considered the universal donor. Most often in the world it is required for transfusion of IV with a positive Rhesus factor.