How is a personality formed?

A person is like a layer cake. The bottom layer is the basis given to us by nature. It consists of genetics and temperament. Although a genetic predisposition is passed down from parents, it does not define our future. The next layer is the child's early development, his or her traumas and decisions that shape character. Yes, character is indeed formed by traumas, and that's okay (parents can breathe a sigh of relief). And then life gives us numerous events, people, and experiences, and that's the next layer of a cake. It is superimposed on the previous "layers" and the result is a unique, special and inimitable person.