Genetic question
Both Mrs. Smith and Mrs. Jones had babies the same day in the same hospital. Mrs. Smith took home a baby girl, whom she named Shirley. Mrs. Jones took home a baby girl, whom she named Jane. Mrs. Jones began to suspect, however, that her child and the Smith baby had been accidentally switched in the nursery. Blood tests were made: Mr. Smith was type A; Mrs. Smith type B' Mr. Jones type A; Mrs. Jones type A; Shirley type O; Jane type B. Had a mix up occurred? Why did you answer the way you did?