A couple with a newborn baby is troubled that the child does not resemble either of them. Suspecting that a mixup occurred at the hospital, they check the blood type of the infant. It is type O. Because the father is type A and the mother type B, they conclude that a mixup has definitely occurred. Are they correct? Give reason for your answer.
They are not correct. The father with blood group A has genotype IAIO. The mother with blood group B has genotype IBIO. Hence, the possible genotypes of the children will be IAIB, IAIO, IBIO and IOIO. Thus, the possible blood groups of children will be AB, A, B and O. Hence, if the father has blood group A, and the mother has blood group B, it is possible for them to have children with blood group O.