What is the topic in The Face on the Milk Carton by Caroline B. Cooney?

Cooney's work centers on the idea of adolescent identity. In
this particular case, the protagonist, Janie Johnson/ Jennie Spring, recognizes that her parents
are not really her parents and the process of reclaiming her identity becomes the basis of the
novel. In this light, Cooney's work focuses on the experience of many children who recognize that
the parents with whom they live are not their "real" parents. It is this focus on the experience
of the "real" that becomes the center for these children. If parents and their lives are false,
then everything is open for scrutiny and questioning. It is this condition in which Jamie finds
herself and being able to doubt everything causes her to set out to find out her true identity.
The practical and psychological implications of this form the basis of the
novel.