Bioethics: who owns a body?

Claim: A healthy adult should be allowed to donate a kidney to a family member, because a fully informed, freely made choice to help a relative is the donor's right to make.\nEvidence: A person can live a normal, healthy life with one working kidney, and transplant programs require donors to pass medical and psychological screening before surgery. Living-donor programs also require documented informed consent, and they use an independent advocate whose only job is to protect the donor, not the patient who needs the organ.\nReasoning: Because the donor is screened for safety and gives consent through a process built to catch coercion, the two main ethical objections (bodily harm and pressure from the family) are directly addressed. Once those protections are in place, respecting the donor's own decision honors their autonomy, so a screened and consented living donation is justified.\nCounter-argument I heard and my response: One classmate argued that a relative might feel pressured to donate even if no one says it out loud. I agree that quiet pressure is real, which is exactly why the independent donor advocate and the private medical opt-out exist, letting a donor step back at any point without the family ever knowing the reason.