THE soul is spiritual … on loan from God, so to speak.
Personality and a lot of other aspects of our persona may be a complex mix of heredity and DNA and brain chemistry and electrical currents and a lot of other things.
Personality, for example, can be easily altered by various medications for good or ill. [And not just medications and other chemicals. Electrical stimulation and physical assault, for example can also change personality. Psychoanalysis is sometimes called “The Talking Cure” … meaning that WORDS alone can also change personality.]
Interesting book:
alibris.com/booksearch?qwork=8063959&matches=65&title=the+talking+cure&cm_re=workslistingtitle
The soul is unchangeable … except to the extent that it is affected by grace and by sin.
Thousands of books have been written about personality and how to measure it and how to change it … etc, etc, etc. My library on psychology is at least 1000 volumes and I only have a small percentage of the total that are available. ]
Probably if you did a search, you would find almost as many books that discuss and describe the soul.