Here is the cartoonist Scott Adams (aka creator of the Dilbert cartoon) taking the puzzle of defining what makes you 'you' and giving an interesting reply:
Have you ever wondered who you are? You're not your body, because living cells come and go and are generally outside of your control. You're not your location, because that can change. You aren't your DNA because that simply defines the boundaries of your playing field. You aren't your upbringing because siblings routinely go in different directions no matter how similar their start. My best answer to my own question is this:I would put down Scott Adams' "definition" as an 'aspirational' definition of self. Its purpose is to motivate you to learn and grow. In reality, you are something quite different from what you "learn". I had that driven home to me when my mother developed a brain tumour and the operation to remove it was botched by an incompetent (but licensed) surgeon. It left her with left neglect and other cognitive impairments (she couldn't visually distinguish me from my brother but she could tell by listening and by using deduction, e.g. the clothes we wore who was who). She was still "my mother" but a big chunk of her was gone.
You are what you learn.
If all you know is how to be a gang member, that's what you'll be, at least until you learn something else. If you become a marine, you'll learn to control fear. If you go to law school, you'll see the world as a competition. If you study engineering, you'll start to see the world as a complicated machine that needs tweaking.
I'm fascinated by the way a person changes at a fundamental level as he or she merges with a particular field of knowledge. People who study economics come out the other side thinking a different way from people who study nursing. And learning becomes a fairly permanent part of a person even as the cells in the body come and go and the circumstances of life change.
You can easily nitpick my definition of self by arguing that you are actually many things, including your DNA, your body, your mind, you environment and more. By that view, you're more of a soup than a single ingredient. I'll grant you the validity of that view. But I'll argue that the most powerful point of view is that you are what you learn.
It's easy to feel trapped in your own life. Circumstances can sometimes feel as if they form a jail around you. But there's almost nothing you can't learn your way out of. If you don't like who you are, you have the option of learning until you become someone else. Life is like a jail with an unlocked, heavy door. You're free the minute you realize the door will open if you simply lean into it.
Suppose you don't like your social life. You can learn how to be the sort of person that attracts better friends. Don't like your body? You can learn how to eat right and exercise until you have a new one. You can even learn how to dress better and speak in more interesting ways.
I credit my late mother for my view of learning. She raised me to believe I could become whatever I bothered to learn. No single idea has served me better.
What that hammered home is that we are a meat machine. You mess up the brain tissue and you change "you" into something else. The religious nuts can talk about soul and an afterlife and other fantasies, but the reality is that we have one life in this world in this body and if the body is broken we change and if the body dies we are gone. It is a real mystery that matter can be alive. It is an even bigger mystery that matter can be self conscious. Life is a wondrous thing. I find it really disgusting that religious "know it alls" pound on a book and claim they have all the answers. Why they have is a blighted mind and a refusal to experience the mystery of life, this wonderful, brief gift we have, and the chance to interact with others using the mystery of our minds. Our being alive is truly mind-boggling. To demean this by pretending that some religious doctrine "comprehends" the meaning of life and "surpasses" mere mortal knowledge is disgusting. Life is too precious and wonderful to be captured by the scribblings of some religious fanatics.