What does Jen believe that background is?

From the text:

“Background doesn’t mean Old Family,” said Jem. “I think it’s how long your family’s been readin‘ and writin’. Scout, I’ve studied this real hard and that’s the only reason I can think of. Somewhere along when the Finches were in Egypt one of ‘em must have learned a hieroglyphic or two and he taught his boy.” Jem laughed. “Imagine Aunty being proud her great-grandaddy could read an’ write—ladies pick funny things to be proud of.”

Jen? There's no Jen in the book. Only Jem.