The father has AB blood type and the mother has B blood type, and the child can have A, B or AB blood type. The human ABO blood group system is mainly governed by the chromosomal A, B and O genes, which determine the type of antigens on the red blood cell membrane, A antigens that is, A-type blood, B antigens that is, B-type blood, both have for AB, none for O. The A and B genes are dominant genes and the O gene is recessive. Since the A and B genes are dominant genes and the O gene is recessive, there are only four types of blood types, which are A, B, AB and O. The genetics of people with the same blood type are not the same. People with the same blood type do not have exactly the same genetic type. blood type A can have a genetic type of AA or AO, blood type B can have a genetic type of BB or BO, and blood type AB can have a genetic type of AB. As mentioned above, a father with blood type AB and a mother with blood type B can have a child with blood type A, B or AB.