Question

A man having blood group $A$ marries a woman having blood group $O$ and they have child. What will be the blood group of the child?

Answer 1

Blood group O, is the recessive blood type. It requires both parents to carry at least one 'o' gene. It's genotype can only be OO. The A and B genes are codominant with one another. That is, they can both be present in someone and both the characteristics of A blood and B blood will show. Both will overwhelm 'o' genes if present. Parent A is O, parent B is B. B has two different genotypes, BB and Bo. Bo indicates the presence of a recessive O gene, getting masked by the B gene. If BB, the odds of a child's blood genotypes are as follows: 100% Bo blood type, this would exhibit as a B blood type. If the B typed parent is a Bo genotype, the child's blood genotype odds are as follows: 50% BO, 50% OO. Either a B blood type or O blood type.