A child born to a B blood type and a B blood type may have a B blood type or an O blood type. Most of the children born to blood type B and blood type B belong to the blood type B. There are also a few chances that the child will be of type O blood. The blood type of a child is determined mainly by the genes of both parents. The genes for blood type B are BB or Bo. If both parties are Bo, then there is a possibility that the child will have a certain chance of having blood type O. If one of the spouses is BB and the other is Bo, then most of the children will belong to blood type B and a few will be O. If both parties are BB, the child can only have blood type B.