Question

What can be the blood group of offspring when both parents have AB blood group ?

Answer 1

Answer:

Each biological parent donates one of their two ABO alleles to their child. A mother who is blood type O can only pass an O allele to her son or daughter. A father who is blood type AB could pass either an A or a B allele to his son or daughter.

Answer 2

Answer:

If both parents are cis-AB with their other allele an O then offspring could be O. And other offspring may inherit the O allele (so AO and/or BO).