Ah, I think I can explain. In English it's not uncommon to use a word like "nepotism" in a not-quite-literal sense. Native speakers will understand it just fine, but if you're in the position where you have to go look up the word, then it might be confusing. To get the colloquial sense of it, extend the word "family" to include friends, their relatives, and people who went to the same university but in different years.