I've recently read that the human body regenerates itself every 7-ish years. (Science people, please step in here if I'm completely misinformed). Our cells are constantly being replaced; we are constantly changing.
While I definitely have some more flushing out to do on my thoughts on the relationship between the physical and "metaphysical" "being" of a "person" (lots of scare quotes here that I will need to explicate in a future liberal arts essay), it's an interesting thought if taken to the extreme (or not even that extreme).
We are not who we were 7 years ago, and we are not who we will be 7 years from now; not due to some self-imposed or accidental acts of self-discovery, but because we have physically been, if you will, replaced.
Just sharing something that tickled my thoughts,