Ask yourself this combination of questions: When did your individual body have its beginning, when did the body of you begin in spacetime; is it right to kill another, to harvest the organs and tissues of that other for medical cures without the consent of that other, or is it right to conceive a new individual human (read begin a new individual lifetime), then kill and harvest the body parts of that new lifetime begun? Remember, it is not the intent of the exploiter that determines whether a new individual lifetime has been conceived, though that will be one of the specious arguments foisted in debates such as this.
You will read, perhaps, misdirectional questions like "Can an embryo think; can an embryo feel?" Counter such bilge by asking yourself, since a new zygote/blastocyst can and does sense its environment in the womb and actively seeks life support from its environment, even the woman's uterine lining, isn't it displaying fundamental characteristics of an independent, individual organism; isn't the earliest embryonic manifestation displaying a will to live, to survive?
We are an individual human being in the body first at conception and remain an individual human being in the body until death, artificially or naturally arrived at, along the continuum that is an individual human lifetime in the body begun at conception.