The blood types of parents who have AB children are A, B; AB, A; AB, B; AB, AB. Blood type, the type of antigen on the surface of blood components (including red blood cells, white blood cells, and platelets), is controlled by human chromosome 9. Human A, B, O blood type is based on the antigens contained in the red blood cell membrane to determine, contains A antigen is A blood type, contains the B antigen is B blood type, at the same time contains the A antigen and B antigen is AB blood type, contains O antigen for O blood type. Therefore, if a child is born with AB blood type, the parents can be A and B blood type; AB and A blood type; AB and B blood type or both of them are AB blood type. However, the specific blood type of the child should be determined by the results of the blood type test conducted by a specialized medical institution.