Because it genetically belongs to only you. What comes from you is you. Your blood is your blood. This is the very nature of every individual's uniqueness as it relates to others and even to one's own family, who are the closest kind. Even the wife is not you; the husband... the son is close to you genetically, but he is not you. but a unique, but genetically close related individual. Your stem cells are you. Science does not understand int the least the role of stem cells, It's rudimentary at best. Their narrative is biased to the parent. Those that receive stem cells from strangers do so in peril. Our Father in heaven ordains our uniqueness. This is why our stem cells from our own body is rightful for treating disease.