Honestly, I think "nepotism" and "occupational persistence" are more about how we feel or judge the phenomenon, and what are prior expectations are.

If sons and nephews are bad managers and a business suffers... that's nepotism. If they're good managers and the business succeeds, that's a family business. if the local authorities hire family... that's nepotism, because we have an expectation that it should be done differently.

A lot of words are like this. Positive and negative words with positive or negative associations that we use to describe the same thing... depending on the association we want to emphasize.

But once homo retcom has words... we think in those words. So, we think of nepotism (for example) as this distinct thing, and expect this nuanced definition to account for the negative or positive aspects.

This paper is basically a formalization of that process.