Alright, you appear to have dodged the question by asking a more interesting one. And that’s not a complaint.
I believe the question is this: what is it that endures/perdures?
You brought up the idea of character as something that is made up of how others think of us and as something that defines us. I believe you changed your mind from saying that it is a defining part of us, but not in the way that I think makes the most sense. If what others thought of us defined us and all a particular someone thought of you was nasty things then those nasty things things would define us, and I think that would be a bummer, but something being a bummer isn’t a valid counter-argument.
To illustrate my point I’ll use my 80 year old self again, this time with no siblings. If I come across a picture of my mother holding me in her arms shortly after giving birth to me, I would say that she was very much holding me. But at that point in time, there are very few people who have made an opinion of me at all. My parents sure, and perhaps the doctors, but 80 years later, they’ve all passed away, God rest their hypothetical souls. Yet I’m still me.
Put another way, imagine that everyone you’ve ever known, loved, made eye contact with, accidentally called on the phone or interacted with in any way whatsoever suddenly vanished. You don’t stop being you. Life as you know it would certainly change, but you’re still you.
On to locale. I believe your definition of locale as a definer of identity acts as a sort of recursive function, meaning that what you are at any given moment is dependent on where you were the moment prior. That’s a fancy way of say that you need a smooth 4D snake. Suppose you could teleport, there is a frog that can teleport, and you both have very good timing and cooperation skills. Now suppose that at the same instant, you and the frog teleported to each other’s locations. Have you now become the frog? And the frog you? If you say no, then there must be something else that makes you you.
Now, suppose in your tale of woe about the twins raised in a lab, that one day the scientists came to each of the twins and informed them of their twin, but told them that one of them had to die, and that they had to choose which one would be killed. If the twins were truly the same, this choice wouldn’t even make sense. Killing either of them would be killing both of them. But they aren’t the same person. Choosing the other twin to die would be an act of self-preservation, and choosing themselves would be an act of self-sacrifice, because they each have an independent self. Their themness is the defining factor between them.
So if it’s not location, character, physical bits nor genetics, that endures/perdures then what is it?
I say personality. Personality is what I’m defining to be the part of you that makes you do any given thing in any given situation. If, at any given moment, there was something that resembled you, then it would be you if and only if it would do the same things you would do and it wouldn’t be you if wouldn’t do the same things. This even applies to normal progression through time whether you’re a endurantist or perdurantist. You are you from a moment ago because you’re doing the same things you would a moment ago if you from a moment ago were at this moment now.
I’ll add a slight caveat just to be safe. You require active subjective experience in addition to your personality. To see what I mean, imagine that perfect atom-for-atom clone of you were created. This clone would do the same things you would do, so in a sense you would be the same person, but if put in the same afore-imagined position as the twins where you and the clone had to pick which of you were to be killed, you would see that you don’t view the clone as the same person as you. I stated earlier that between the twins, “Their themness is the defining factor between them,” but I didn’t really define what themness was. Themness is active subjective experience. If I have a clone, then I’m still me, and the clone’s not me because I am actively subjectively experiencing myself, and not the clone. I’m seeing out of my own eyes and thinking my own thoughts, and my clone is seeing out of his eyes and thinking his own thoughts, so we have our own distinct themness.
So to answer your question, we do not remain the same, but we do remain ourselves, and from moment to moment what endures/perdures is our personality and our active subjective experience.
But perhaps you have your doubts.
Awaiting your response,