[erelde]

That question is exactly what I'm asking, what is "myself" and what is "the environment as defined around myself".

And I'm pretty sure there's no clear answer, but the question and reasonings ensuing are interesting.

By one definition, my possessions, my experiences, my social network would be part of myself. So changing my brain wouldn't be changing myself per se if those remained the same.

Another definition would be the strictly biological body, and of course changing the body would be changing the self.

But there's a fuzzier definition where something in the brain brings up "consciousness" and a sense of self, if I change something in the brain that isn't that particular part, the sense of self, have I changed the self or not?

(I can see my French high school teaching re-surging here...)

[Retric]

Self has no universal meaning robbing the question of any real value. You could include or exclude gut bacteria from you just as easily as you include or exclude identical clones, but that's just an outgrowth of your definition and says nothing about reality.

[ZeroFries]

All abstractions leak eventually. You can't separate anything in the universe from everything else. To clone yourself perfectly (for all time-slices going forward), you'd have to clone the entire universe.