Janie

The Janie Johnson series is a four book series by Carolyn B. Cooney about a young girl named Janie Johnson who sees her own face on a milk carton and realizes that the people who raised her are not her real parents. In fact, she was stolen from her birth family (the Springs) in early childhood and the Springs want her back. The series follows the young Janie in her attempts to figure out the truth about her origins and decide who she wants to be from now on. Will she remain Janie Johnson, living with the family that is not truly hers, or become Jennie Spring and finally bring peace to the family that birthed her? The first book in the series was made into a Made for TV Movie in 1995.

The series consists of the following titles:

The Face On The Milk Carton (1990)
Whatever Happened to Janie (1993)
The Voice On The Radio (1996)
What Janie Found (2000)

Tropes used in Janie include:

All Men Are Perverts: Reeve continually tries to imagine ways to convince Janie, who is not ready for sex, to change her mind.
Black Sheep: Janie or Jennie when she rejoins the Spring family in Whatever Happened to Janie.
Bittersweet Ending: How the main series ends; Hannah is finally arrested for her crimes, giving the Springs closure, and Janie marries Reeve following a genuine reconciliation. Janie also fully accepts her Jennie Spring identity. The Johnsons, however, can't fully escape the bad press of Hannah's actions; they and the Springs have also lost many years spent with Janie or Jennie because of Hannah's manipulation.
Changeling Fantasy: An unusual subversion; Janie has a serious crisis of identity when she discovers her real parents.
Could Have Avoided This Plot: Most of book one has Janie struggling with the idea that her parents may be kidnappers and hides her quest for the truth. This is reasonable at first, not-so-much when they tell her that their daughter Hannah claimed that Janie was their granddaughter and dropped her off after running from a cult and it becomes clear that Hannah was the one who actually did the kidnapping. Book one ends with her finally telling them about the photo she saw on the milk carton, and that it matches the dress in the attic. Their response is why didn't she tell them sooner? The Johnsons start reasoning, with horror, that it's more than possible that Hannah kidnapped little Jennie Spring, and encourage Janie to dial the Springs' phone number to find out if it's true.
Creepy Child: Young Hannah.
Didn't Think This Through: Reeve gets a really stupid moment while narrating on college radio in book three's opening chapter. His mind goes blank when he's on the air, and he needs a story. So he talks about how his high school girlfriend realized she was a kidnap victim. On the day that Janie is visiting him at college. Janie gives him a What the Hell, Hero? because he turned her recent trauma into college radio fodder, breaking up with him.
Early Installment Weirdness: Hannah's backstory started off as an impressionable 16-year girl suffering from white guilt who needed parental permission to join a cult. Later on, it was apparently a college student who felt isolated and far from home. Similarly, her motives for kidnapping Janie seem to change from 'cult mission' to 'loneliness' to 'batshit insane' according to the whims of the author.
Face on a Milk Carton: Janie finds her own picture on the milk carton. This is how the story begins.
Fiery Redhead: Janie, also her sister, Jodie and their brother.
Make-Out Point: nicknamed "Sexual Overlook."
Overprotective Dad: Justified trope. The Springs are overprotective because their daughter were stolen when she was little.
Plot Allergy: Janie is allergic to milk. One day, feeling rebellious, she takes an offered milk carton from a friend. Then she sees her face on it, as a toddler. She does get sick, for more reasons than the obvious.
Raised by Grandparents: The parents who raise Janie reveal that they are not her parents, but her grandparents, and that her real mother is their daughter, Hannah. This turns out to be a lie that Hannah told them to make them accept the "replacement daughter" she stole for them.
Riddle for the Ages: Lampshaded by Janie; she was three at the time that Hannah kidnapped her, old enough to know not to go with strangers. Just how did Hannah convince her to come with her and leave the mall? Why did the Johnsons keep the dress in the attic? Her siblings don't have answers for this in the second book.
Religion of Evil: The cult Hannah joins.
Technology Marches On: At least half of the first book could be resolved if Janie could have just Googled herself.
Smithical Marriage: Subverted when Janie goes to a hotel with Reeve.
Wham! Shot: On a hunch, Janie investigates the family attic, to ease her paranoia that surely she's not a kidnapped child. She finds a polka-dot dress meant for a toddler, the same one in the photo. Janie remembered it, which was how she recognized it in the photo of Jennie Spring. While Reeve says there may be another logical explanation, he realizes what Janie is implying.