Why doesn't Jane answer her stepfather?

Jane most likely has some sort of troubling past with her stepfather. What that is, is never directly stated but there are enough clues that point to some sort of sexual abuse. In the previous chapter there is a remark about the fact that the stepfather was a 'booze hound' and used to run around the house naked. When Holden asked Jane if her stepfather had sexually abused her, however, she denied it.