Question

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.

Answer 1

They are not correct. The father with blood group A has genotype I^AI^O. The mother with blood group B has genotype I^BI^O. Hence, the possible genotypes of the children will be I^AI^B, I^AI^O, I^BI^O  and I^OI^O. 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.