Hank Green just did a follow-up about a question about “who has the most DNA”, where he back pedaled heavily on his previous attempt to answer.

I learned, as he had, that sometimes bone marrow transplants don’t take and one option is to administer another, or several, which could make you much more chimeric than the average stem cell recipient. But I don’t understand how the marrows don’t end up fighting each other in a death match. Is that a special property of marrow?