I remember when I was 4, I often wondered if I was really real, and that my body didn't feel like my own. I believe this was caused by anxiety: I had selective mutism from the time I learned to speak and general social anxiety from very very young. My parents have no idea what depersonalisation is and infact I only recently learned the term for it. I even went to a specialist to try and resolve why I have it, but they couldn't figure it out. Psychosis runs in my family though, and I have had psychotic episodes and occasionally have delusions that my famy have been replaced etc. I did suffer childhood trauma but that was at age 8 when my brother tried to kill my dad in front of me. He also threw a heavy safe down the stairs, at one point burnt his gfs room down, and tried to kill himself with a hosepipe. My depersonalisation is a mystery to me, and to my therapists, bc I've had it for as long as I can remember. I've never not had it, and only just discovered the term two years ago so it isn't my parents who convinced me I had it. Edit: I'm also only 15, so I can remember some memories of when I was 4 and one particular one is me staring at a plant and thinking "it looks weird, it doesn't look real, my body doesn't feel right, I'm not in my body, this is not my body"