This questions stirs me deeply.

I am not the person I once was and yet i am still the same person I always was.

My ex-wife used that as an excuse to divorce me. She told me, when I left Moronism (oops, Mormonism), that she married a Moron (oops, Mormon), and I wasn't the same person anymore.

I disagree. Of course I'm the same person! I was just progressing in knowledge.

You can change the exterior but you can't truly change what is inside the person.
Everyones actual body changes from time to time, cells die and are renewed regularly but still we remain as recognizable Human Beings on the inside no matter what we attempt to change on the outside.
Emotionally, psychologically, etc, WE can alter but still, inside, we remain the same.

I am 64 years old and I am not the same person I was when I was 24, or 34, or 44... the only thing constant is change.

I don't think it is possible to change Everything about oneself. As we live and experience different things we change our perspective and opinions about the world.

Did this person also change their DNA? If so, then yes.

Sometimes one can find themselves being who they think they are suppose to be, letting family, friends, even society pressure them. When we feel uncomfortable in our own skin and decide to take a different path, this is when we may become who we really are. Don't confuse growth with change. Excluding most conservatives, most people do grow and change their way of looking at some things as they gain experience and knowledge. IMO

So the moment you see that intervals—that space—is connective, you can understand at once how you are not just to be exclusively defined as a flash of consciousness that occurs between two eternal darknesses, which is the popular common-sense view which Western man has of his own life: that you consider that in the darkness that comes before your birth there was no you, and in the eternal darkness that follows your death there is, likewise, no you. And I’m going to discuss these matters not by appealing to any special, spooky knowledge—as if I had been traveling on the higher planes and knew all my previous incarnations, and therefore could tell you authoritatively that you are much more than this individuality. I’m going to do it on a basis of complete common sense that everybody has access to the facts, and that just what you have to realize is that life is a pattern of immense complexity, and what you call ‘yourself,’ as a living organism—say, I am my whole body, at the very least—now what is that body? That body is recognizable, and I recognize my friends when I meet them again (with luck), and you recognize me. Although, the last time any of you saw me, I was absolutely something entirely different from what I am now; just as the flame of a candle is never a constant. A flame of a candle is a stream of hot gas. Only, you say “the flame of the candle” as if it were a constant. Well, it is a recognizably constant pattern: the spear-shaped outline of the flame and its coloration is a constant pattern. But in exactly the same way, we are all constant patterns, and that’s all we are; the only thing constant about us at all is the doing rather than the being. It’s the way we behave, the way we dance; only there’s no ‘we’ that dances, there’s just the dancing. Just as the flame is the streaming of hot gas, just as a whirlpool in a river is a whirling of streaming water. There is no thing that whirlpools, there is the whirlpool.

Alan Watts

No, but it may mean they've finally become who they really are.

It seems to me religious people normally don’t change much. They are always trying to hold the same ideas they’ve had their whole life. Conservative.

I’m definitely not the same person I used to be. For example, when I tell people I was in the Army, I say it was a lifetime ago (it was 1985-1990). It truly feels like it was another person’s life and I was just an observer. This is true about soooo much of my past.

So I’d answer yes ... nothing about me is the same.

It depends on how you define a person.

If a person is their experiences then with each experience a new person is born.

If a person is more than their experiences, but how they choose to act then every decision births a new person.

A person is only a recognition of experiences and values expressed over time for an instant.

everyone is always changing, sometimes better sometimes not. You can either accept the changes or move on.

Past experiences dictate who we become, so unless there is some kind of clean slate on the brain and memory of everything is wiped I’d say not possible.

...or the person they changed into was who they were all along! I can see certain behaviors, appearance and beliefs changed, but the basic personality traits will show up, in unguarded moments!

I've changed everything about myself more than once. Apparently I took a wrong turn, probably should have made that left at Albuquerque.

I hope so. Otherwise, there really isn't much point in becoming the person you want to be, huh?

To me it becomes clear when I reunite with friends I haven't seen in years; we never really change that much.

No, but they may react to specific people differently.

Yes and no. It's impossible to change everything about yourself, but it's also impossible to change nothing. There is probably less difference between a person who changes a lot and a person who changes little, than between an infant and an octogenarian.

Change is a part of being. Time is merely a measurement of change. The course of one's change is a measurement of character. It is impossible to outgrow one's roots.
So a ship may alter it's course but it's still a ship.

It means they have become possessed by demons.

Everything?... not possible...now one may attempt reinventing themselves...but no...change....one only changes the appearence...the image....nothing more but the superficial...deep down under all the trappings is the same person..with the same memories... experiences...likes..dislikes etc....so..theres ur answer.

We all change as time goes by. I have looked back on the foods I liked as a kid, now I don't eat some of them.

The brain is by far the most plastic and changeable organ in our bodies. The brain you have today is not the same brain you will have tomorrow. So radical change is quite possible, tho rarely enacted, short of major revelations and realizations causing them to happen.