The blood type of a child with blood type AB and blood type O may be either A or B. If both the father and mother have blood types AB and O, then the blood type gene of one of the AB blood types is AB and the blood type gene of one of the O blood types is OO, then the blood type gene of the child of both may be AO or BO. Among the blood group genes A, B, and O, two of them, A and B, are dominant genes, while the blood group gene O is a recessive gene. If the blood group gene is AO, then the child’s blood type will be A. If the blood group gene is BO, then the child’s blood type will be B. Therefore, children with AB and O blood types may have blood type A or B, but the exact results are subject to the final test results.