I am traumogenic (trauma created/clinical DID) plural system. It is highly likely that I never had a "core personality" that I was born as and instead have always had either an infant mental state or multiple personalities. (During the time most babies begin to form a coherent personality, I formed several. It is possible that not every system forms like this but highly like I did)
Every time I've felt I was singular, I've experienced mental walls, amnesia and other DID symptoms. If someone could do a "I'm singular ama" that'd be cool because I have questions too. :)
I used to think it was an exclusively spiritual thing. I've been long socially viewed as somehow different. What finally broke the denial for me as having my alters get FURIOUS at me for inviting a person who ended up being dangerous (who is also a system) to live with us. I also had an extremely negative experience with other plural systems years ago but didn't want to accept that I was like them because of how dangerous and harmful the experience was. Thankfully, I found out that there are many many many systems out there and recieved coaching/support from other systems who have not caused violence to me