C237 What Was His Background

"The old man's blood type is A, he had a record here before" The doctor flipped through the file again. "Since it's Type A and Type B, the child might be Type A, or Type B. Type AB, or Type O, but it was absolutely impossible for it to be RH negative blood, while the Third Young Master had RH negative blood. This means that the third young master is not the old man's child