Grew up in Chapel Hill (university town in NC) in the 80s. I never heard anyone do “yo momma” jokes seriously, and I think if I had, I would’ve laughed at the person for being a dumbass, not taken it seriously.
As a teacher, I hear fights started over this sort of thing sometimes. IEvery time I’ve heard it, it’s been African American kids, and it’s more often girls than boys, and they tend to be grooming insults (“Your momma doesn’t do her hair every day!”) that I don’t always understand. Sometimes they’re insults about skin color.