Question

Ralph has type B blood and his wife, Rachel, has type A blood. They are very shocked to hear that their baby has type O blood. They think that a switch might have been made at the hospital. Can this baby be theirs?

Yes, if both parents are heterozygous for their blood types.
No, this baby is not theirs.
Yes, if both parents are homozygous recessive.
O Yes, if Ralph is homozygous and Rachel is heterozygous.

Answer 1

Answer: Yes, if both parents are heterozygous for their blood types.

Explanation: A child with type O blood can have parents with type A, type B, or type O blood, but not type AB. Conversely, if two parents both have type O blood, all their children will have type O blood.