As far as we know, Clarisse seems to get most of her information about the way life used to be from her uncle. She talks about her parents some when she is speaking to Montag, but she talks way more about her uncle and what he says.
For example, her uncle says 17 year-olds are always crazy. More to the point, he tells her how kids did not used to kill each other for fun. He talks about how people used to believe in responsibility.
He is the only one we really hear about who tells her about how things used to be.