My very first job after chemistry school was working at the Fred Hutchinson cancer research center on the bone marrow transplant unit. There are very elaborate tests to determine if a bone marrow donor is an appropriate match for a recipient, and you always look for a compatible donor first amongst the immediate family. We had one case in which a child needed a donor and the results of the testing demonstrated that two out of the four children had a different father, unbeknownst to the husband/father of the family, and the mother begged the oncology team to not reveal that to the father.
