@machiavelli1738: I also have a non-Greek, OOS first-year student, who has not seemed to lack for a social life. Early in the Fall Semester there is a huge activities fair, where clubs and organizations have tables or booths; you will have the opportunity to engage with lots of different people if you choose to take advantage of some of these clubs and organizations. There are also off-campus music/dance venues in both Chapel Hill and the adjacent town of Carrboro for socializing. Additionally, even though my first-year is not a member of a sorority, she seems to get a fair share of invites to fraternity parties; so there should be opportunities in that regard if you want them. Finally, the abundance of IS students can work to your advantage: my daughter found her roommate (from Chapel Hill) on a Carolina 2020 Facebook page, and got linked in to an immediate group of friends through her roommate. Although at first it might seem that every student you meet is from Charlotte or Raleigh, you should quickly expand your acquaintances to encompass both IS and OOS students.
As far as the “southern culture” thing goes, Chapel Hill and Carrboro are a bit more progressive/tolerant than much of the rest of the state. I think you will find the local culture more similar to Boston than you might otherwise suppose.