I honestly don't know how to present this argument in any form, I can understand the logic i'm using but I can't understand how to put it into words. My previous attempts resulted in a flawed idea, I will try one more time but I can't guarantee its correct.
If you cut off your arm, you "own" it, your property. Pretend this arm is a seed that you very well "own", you grow it into a full vegetable which is also yours. The arm is yours and you told the arm (it's cells) to manifest in a manner that resembles a growing human fetus, the fetus grows in to a full human. You owned the seed (arm), you used the resources to make it grow into a vegetable (Human), theoretically you should own this result as well.
It doesn't matter morally because those are your cells, therefore your organs, your brain. Its not the same as a twin because the clone was grown from something you own, something that's you. A twin is simply a zygote split in half, nothing is grown from something that one person owns, that came directly from one person. (This second paragraph is definitely flawed considering the first one, but again I hope you can understand.)
I still hold by "if it has a brain than you don't own it, if it does then you don't"
You can cut off your arm and still be a sentient person, hell you can remove plenty of organs and still be kept alive in the hospital, but if your brain is removed then you're gone.
The brain is the person and the body is just the shell it uses, if its just an arm thats grown, its as ethically right to say you own it as to say you own a branch that you got from your backyard, now to say you grew a full person, it would be like finding a baby in your backyard. You still don't own it.