Sim's parents end up going to university too even if they weren't enrolled

[mockingjay93]

My sim just graduated from high school and successfully enrolled in University. The thing is, I've noticed that his parents are also in the "people he knows at university" list. They're adults and they've got careers of their own and everything. Aren't they meant to be at home? Why did they also end up going to the university if I didn't enrol them in courses to begin with?

[Sherry]

I dunno what could cause it, but I imagine it would be hilarious like:
"Mom? dad? Is that you? Owh Plumbob! I thought you'd said I could finally be on my own at the university?"
"Yeah, you know? We are worried..."

Anyway, on more serious comment from me, could it be because your sims' parents are actually saved in the 'bin'.
I did have a double sim once too, I think it was because the family was saved in the bin and I didn't delete the bin file after I placed them on the town.