Liar by Justine Larbalestier

Micah is a liar. She’ll tell you so herself. She’s lied to classmates, teachers, her parents, spinning tales about being born a hermaphrodite or having an arms dealer for a father. But this time, she promises, she’s telling the truth. She’ll tell you about her relationship with popular high school student, Zach (who may or may not have been her boyfriend) and what she knows about his brutal murder, about her mysterious relatives in upstate New York, and the terrible secret she’s been carrying for years.
Micah is a puzzle, constantly professing her honesty while backtracking over her story to correct lies and possibly add more. Was she really dating Zach? What are those pills she must take everyday? Is any of this tale truthful or simply the ramblings of a troubled young teen? The only thing that we know for sure is that Micah is one talented liar.