Question

Mr. and Mrs. Black had a baby last night in the local hospital. At around the same time, Mr. and Mrs. White also had a baby in the same hospital in the room adjacent to the Blacks. Both babies were girls, both weighed about the same, and looked very similar.
The following day, a nurse brought the babies from the nursery to the new parents, but Mr. and Mrs. Black insist that they got the wrong baby! To test that, everybody's blood was drawn to establish the blood types. Here are the results:
Mr. Black has blood type O Mrs. Black has blood type AB The baby in Black's room has blood type O
Mr. White has blood type A Mrs. White has blood type B The baby in White's room has blood type A
Try to solve this situation using what you have learned about the alleles and genotypes coding for these blood types to establish if the Blacks' and Whites' babies were switched. Use the Punnett squares to prove your point.