Does child have to have the exact blood group of one of his parents?

No, it is not necessary for a child to have the exact blood group of one of their parents. The blood type of a child is determined by the combination of genes inherited from both parents. The ABO blood group system classifies blood into four types: A, B, AB, and O. Each blood type is determined by specific antigens present on the surface of red blood cells. When a child is born, they can inherit different blood type alleles from each parent. For example, if one parent has blood type A (genotype AA or AO) and the other parent has blood type B (genotype BB or BO), their child could have blood type A, B, AB, or O, depending on the combination of alleles received. The Rh factor (positive or negative) is another component of blood typing. This factor follows a similar inheritance pattern, where the child can inherit the Rh factor from either parent. The blood type of a child is determined by a combination of genetic factors inherited from both parents, and it is not a requirement for a child to have the exact blood group of one of their parents.