Mary’s parents both have type AB blood but she has blood type A. John has type B blood, but his mother had type A blood. What are John’s and Mary’s 2 letter genotypes for their blood type?
A father who is blood type AB could pass either an A or a B allele to his son or daughter. This couple could have children of either blood type A (O from mother and A from father) or blood type B (O from mother and B from father).
