There is no such thing as a bone marrow matching success rate, which is generally referred to as the probability of full compatibility in medical terms. This depends on the choice of the match, the closer the kinship with the patient, the higher the probability, and vice versa, the lower the probability. Half of the genes in the human body originate from the parents, so only 50% of the parents or children are compatible when they are selected as a match. When identical siblings are selected, there is a 100% match. If you choose an ordinary biological sibling, it may be a full match or only a 25% match. If matched with an unrelated person, the probability of a full match is even lower, ranging from 1 in 10,000 to 1 in a million, so clinically it is better to choose the family member who is closest to the patient’s blood relatives.