Children with blood type A and blood type B may be type A, B, AB or O. The blood genes carried by a person with type A blood may be type A or O, and the genes carried by a person with type B blood may be type B or O. Therefore, the following 4 situations will occur: 1. The child of a person with blood type gene A in combination with a person with blood type gene O may be of type A. 2. If a person with blood type B combines with a person with blood type O, his/her child may be type B. 3. The child of a person with blood type A and blood type B is likely to be AB. 4. If a person with blood type O combines with a person with blood type O, the child is likely to be type O. Thus, a child born of blood type A and blood type B may be type A, B, AB, or O, although the probability of type O is low.