Self-Ownership

I had an assignment in my Senior Seminar class where you write, minimum of 250 words, answering a single question usually related to politics but general in nature. One question was whether someone should be able to sell their own kidney for their own gain, even if somebody else possibly related to them needs it to live. This is what I wrote:

Yes off course you should be able to sell your own kidney. It is your body, your kidney. What claim does somebody have towards your person? You're parents did create you in the sense you inherit their genes, which created your kidney as well as raised you. But you are not just your genetic endowment or environmental influences. If you were, you wouldn't be the same person today as you aren't the same person physically throughout your life. Almost every cell in your body changes every single year, yet you are the same person. How is this? It is because you have memories of your past selves. Your identity is your stream of consciousness, a continuity of experience which belongs to you, not everyone else. That is why you own your body, nobody created you. You are you by virtue of continuing to exist, persisting through space and time as an objective real entity. Nobody experiences the world exactly as you do. That private aspect of human nature, even if we can all know or empathize about, belongs to you. It is you who uses that kidney to maintain your life and felicity. You may do as you please with it for your own good to further your goals. If others want it, then they ought to convince you to fork it over. The argument that you are allowing someone else to die by not giving your body part assumes what it denies, that a person has a right to live and do what they can to secure it. Well, so do you. Whose life and happiness is more valuable? There is a danger of that question becoming an arbitrary decision of government. Who will live and who will die.