The existence of four blood groups was proven by scientists at the beginning of the twentieth century. Studies have shown that a child's blood type will depend on the parent's blood type, that is, it is genetically inherited.
What blood types are there
As a result of the research of Austrian scientists Karl Landsteiner and his students A. Sturli and A. Von Decastello, a blood classification system called "AB0" was created, which is still used today. According to this system, there are four blood groups:
I (0) - it is characterized by the absence of special substances in the blood - antigens A and B;
II (A) - antigens A are present in it;
III (AB) - characterized by the presence of type B antigens;
IV (AB) - there are antigens A and B in the blood.
This discovery helped to exclude losses from blood transfusions, since due to different characteristics, the donor's blood could harm the patient's body.
What blood group will the child have?
In further research, scientists have proven that the principles of obtaining a blood group in a child and other genetic characteristics will be identical. According to Mendel's laws, formulated in the second half of the nineteenth century, parents with the first blood group produce children without antigens A and B (that is, having the first blood group). Parents with the second blood group have children with the first or second blood group. Spouses with the third blood group have children with the first or third blood group.
Parents with the first or second, or the first and third blood groups have children with one of these groups. If one of the spouses is of the fourth blood group, the child cannot have the first blood group. If one of the spouses has the first group, they cannot have a child with the fourth blood group. Spouses with the second and third groups have children with any blood group.
Principles of inheritance of the Rh factor in blood
The Rh factor is an antigen (protein) that is located on the surface of red blood cells. It is present in the blood of approximately 85% of people, that is, they are Rh positive. In the absence of this antigen, one speaks of Rh-negative blood. These factors are denoted by the letters Rh: negative with a minus sign, positive with a plus sign.
If both parents are Rh negative, they can only have a baby with Rh negative blood.
A positive Rh factor is dominant, and a negative one is recessive. If both parents have both traits in the genotype, they will be Rh positive. However, in this case, there is a probability (25%) that the child in this case will have a negative Rh. That is, if both parents or one of them has a positive Rh factor, they may have a child with both Rh-positive and Rh-negative blood.
