Are you suggesting by this line of thinking that the soul is an inheritable trait like a big brain or something else?
Naturally, we're deep into the realm of speculation at this point, but we have souls because the first man was given a soul, and it thereby became a trait of his offspring and descendents thereafter. How that occurs in each case, I won't speculate. Shall we call it a mystery? Or would you like to propose an answer?
If you were proposing that the soul has a genetic component, which it sounded like you were, one could genetically search for and possibly isolate the genomic elements responsible. Take for example, Alzheimer's, Parkinson's, diabetes, or Huntington's disease.
