Personally, I detest raisins. Just don't like 'em. Never did, never will.
I like grapes. I like other types of dried fruit. But dried grapes, bleagh. I don't know why, exactly.
I hate raisins to the point that I'll go to no small amount of trouble to pick them out of things like trail mix where the evil little wrinkly bastards have no business lurking. I mostly just skip foods contaminated by raisins.
Anyhoo, that's all beside the point...
OK, let's say you're 6 year old Brun's Mom in a grocery store. You see a sale on raisins.
"Brun, do you like raisins?"
"I don't know. They look gross."
"OK, then. We don't want to waste food, so I'm not buying them."
And thus raisins do not enter the house, and Brun ends up somewhere in her mid-20s without encountering them again.
Even in a household that isn't poor, it's quite plausible that raisins wouldn't re-appear once rejected by a kid who was probably always pretty picky about what she eats anyway.
Also, although time is hazy in the QC universe (as well as its other relations to our universe), the California Raisins craze was huge in the late '80s and was pretty much over by the time Brun was born.
In any case, it's nice to learn a little more about Brun and Clinton.