We say that we inherit our blood group from our parents. Many a times, we see that the child's blood group is not the same as that of its mom or dad. Even in a family of four people, all four, sometimes, have different blood groups. How is that possible? We'll try to understand in the most simple way how is blood grop inherted. What is genotype? What is an allele? By knowing the genotype for blood group, of both the parents, we can easily predict the various possibilities of the blood group, a child can have.