Around 1978, I watched the TV BBC Program Series “7 Up”. It was based on 7 year old kids from different social/economic backgrounds in the UK. They videotaped interviews of these kids that are now in their 60s and they have been interviewed every 7 years there after. The latest interview was at age 63 years old. You can guess pretty accurately on how they will turn out as adults.This is a very well written article from The NY Times: https://www.nytimes.com/2019/11/27/magazine/63-up-michael-apted.html
Have you really changed your personality after age 7? I believe we have 99.9% of our emotions before age 8 and after age 8 we just repeat them. We are emotionally driven beings.