Board Thread:General Discussion/@comment-26153610-20150305125025/@comment-71.202.210.157-20150305191506

My guess is since some Grounders still are affected by radiation as in being born with deformities or giving birth to children with them they are not the ideal candidates for bone marrow transplant especially for a people who can't naturally filter radiation. The Sky People can filter radiation more efficiently than Grounders so using their bone marrow wouldn't pose a risk like using a Grounder's would because like in real life one bad batch of marrow can kill or harm many more especially to a group that has very few people it is too much of a risk to take. That is why when they found out the Sky People's biology was better it was perfect for them to harvest them with no risk to their people.