Blood type in humans is an example of trait that has multiple alleles. The alleles for type A blood and type B blood are codominant, and type O blood is recessive to both type A and type B. If a girl with type AB blood has a brother with type O blood and a sister with type B blood, which of the following genotypes could it be possible for their parents to have?

AO and BO
AB and OO
AB and BO
AO and AB

Question

Blood type in humans is an example of trait that has multiple alleles. The alleles for type A blood and type B blood are codominant, and type O blood is recessive to both type A and type B. If a girl with type AB blood has a brother with type O blood and a sister with type B blood, which of the following genotypes could it be possible for their parents to have?

 AO and BO
 AB and OO
 AB and BO
 AO and AB

anonymous · Answer

O is essentially a blank slate for blood, it has no antibodies and no antigens. Based on that, the parents most likely had AB and AO