At this point, nearly all of my cells have been replaced many times over from when I was first conceived. My physical body has undergone a wide variety of changes over time, mostly due to the normal aging process. I have changed so much that, as I've mentioned earlier, I don't like shaving off my mustache and goatee because I don't recognize the person behind them anymore.
More so, my thoughts, values, and ideas have changed over time. Students of mine from my first few years of teaching would be shocked at the differences in my current classes. Certainly, some parts would be recognizably familiar, but I've changed quite a bit in my teaching practice over the decades--personally, I believe for the better. Nor are my thoughts on a variety of subjects the same as they were even a few years ago (and I have these blogs to look back on to see precisely what has changed and what has not).
I still resolutely believe that I am me. However, I am clearly not the same me that I was before. In general, I'm quite a bit happier with the changes, but I cannot help but wonder if I am missing pieces of myself in this process of continual self-evolution. I am also interested to find out who I will be in the future. I will strive to make certain that it's someone I would like.