Around 1978, I watched the TV BBC Program Series “7 Up” on the PBS. It was a video documentary based on a group of 7 year old kids from different social/economic backgrounds in the UK. Thereafter, the producers did video followups with these interviewed kids every 7 years.
The latest interviews were at age 63 years old. Many times by just watching the video you can pretty accurately guess on how these 7 year olds will turn out as adults.
Have you really changed your personality after age 7 ? I believe we have created 99.9% of our emotions before age 8 and after age 7 we just repeat them. Emotions direct our behaviors. We are emotionally driven beings.
This a 47 minute video:
This is a well written article from The NY Times: https://www.nytimes.com/2019/11/27/magazine/63-up-michael-apted.html