Dear student,
The child gets its blood group from both its parents. The blood groups are controlled by the gene known as I gene located on chromosomes. This gene has two forms called alleles and child receives one form of this gene from father (parent 1) and one from mother (parent 2). Under the common ABO blood type, a person 's blood type can be A, B, AB or O.
If a mother has blood group A i.e. it can be either IA IA or I A I o . The blood group of father is A i.e. it is IA IA or I A I o . Therefore, two parents with A blood type can produce a child with either A or O blood types.
Regards.