Mary has type A blood and her husband has type B blood. Her husband’s parents both had type AB. They have three children, one with type A, one with type AB, and one with type B. Relatives suspect that one of the children was adopted.

Question

anonymous · Answer

What is the parents blood type? Which child is adopted?

anonymous · Answer

The question is not which child was adopted. 

Mary is a skank. And she cheated on her husband. 
One of these children is not his child.