It's not uncommon for adopted children to go searching for their birth parents. In fact, in most states, laws have made it easier for them to do so.
But sometimes, the circumstances that separate a parent from a child can be much more complicated - and baffling. For instance, imagine discovering that the child you loved and raised for years wasn't really your own.
Correspondent Erin Moriarty has the story of two families, a father's hunch and an investigation that transformed their lives forever. This broadcast first aired last December.
Kathie Morgan remembers the day her baby sister, Shirley, was brought home from the hospital.
"I remember first seeing her in the bassinet, and I'm 8 years old, and I see the dark hair – and even, for our babies, [it] was strange," says Kathie.
Even though Shirley looked nothing like her seven other siblings, there seemed to be a logical explanation. Their grandmother was French-Canadian and had similar coloring.
But Shirley's own father, Jim Morgan, never could accept that explanation, but he managed to keep his suspicions to himself.
"In his heart, he knew it just did not fit that that was his daughter," says Kathie. "He just decided they were given this gift of a baby. He's going to help mom raise her with the rest of us and make the best of it."
Forty years passed, and the Morgan kids had kids of their own.
At the age of 80, Jim Morgan fell ill with a serious heart condition, and was moved into a nursing home. Finally, after he was told he had just weeks to live, he blurted out what he had feared for years - that Shirley wasn't his child.
Kathie was determined to set the record straight, and give her father some final peace, so she scheduled DNA tests for her father, mother and Shirley.
The results took everyone by surprise: Jim Morgan was not Shirley's biological father. And Jean Morgan was not her mother.
This meant only one thing. Somehow, the Morgans had come home from Campbell County Memorial Hospital with the wrong baby 43 years earlier.
For Shirley, the news was overwhelming, so much so that she didn't want to speak to 48 Hours about it.
And although Kathie loved her sister Shirley, for her, there was only one thing to do: "I've got a sister out there, and we're going to find her."
First stop on Kathie's search was the hospital, where authorities gave her official birth records from that night.
There was one problem: the name of the other mother was blacked out. Through a librarian, Kathie heard about a way she might be able to read through those blackened out lines. Desperate, she soaked the paper in distilled water and Clorox for two days.
Finally, she was convinced that she had uncovered a significant clue: the name "Polly." Kathie headed to the local library and began checking school yearbooks, searching for Shirley's biological mother.
She found a picture of 17-year-old Polly Munoz in a 1958 high school yearbook, and when she compared that picture with one of Shirley at roughly the same age, she knew she had a match.
But the library was as far as Kathie could go on her own. The problem? Neither Kathie nor her mother had any legal right to see the other woman's birth records. Fortunately, in about 20 states – including Wyoming – a confidential intermediary is able to view birth records and even sealed adoption files.
Confidential intermediary Ann Robinson agreed to take the case, and it took her nearly three hours to track down Polly's daughter, Debra DeLay, who was living in Phoenix.
"I called her and told her that she and another child were switched at birth," says Robinson. "There was dead silence on the phone when I told her."
For Kathie Morgan, the moment couldn't come soon enough. After 43 years, she finally had the chance to meet her sister, Debra. Her parents were also finally able to have their daughter back.
But for Debra, the idea of meeting her new family was terrifying. Since first learning that she'd been switched at birth, she's questioned everything that's ever happened to her.
But there was little time to pull herself together. Debra's father was dying, so she left her home in Phoenix and headed to Wyoming.
"Mommy gave me a big hug and a kiss, and she says, 'We've been waiting for you for 43 years,'" says Debra, when she finally met Jim and Jean Morgan.
"You can take 43 years, you can take different family raising you, you can take all that, but it doesn't erase who you are," says Kathie. "She is so us."
But all eyes were on the moment Debra met Shirley, who had taken her place in the Morgan family.
" I wish Debra had come home with us and Shirley with her rightful family," says Kathie. "I think the girls' lives would have made more sense."
Debra and her single Hispanic mother, Polly Munoz, started out in Worland, Wyoming, only about 100 miles away from the Morgans. Polly later
married and had two more children.
Debra grew up in a primarily Spanish-speaking neighborhood and, according to childhood friends, the tall, blonde woman always stuck out.
She says her childhood was miserable because she always felt like a misfit - because she was white.
A cheerleader and homecoming queen in high school, Debra married soon after high school, but divorced without having children. She ended up in Phoenix 12 years ago.
Debra had the life Shirley was supposed to lead. Instead, Shirley grew up as the youngest girl of eight children in a large, tight-knit Irish clan.
Like the rest of the Morgan children, Shirley went to the local high school. She married young, had three children and later divorced but never strayed far from her family in Gillette. Her children remain close to their Morgan grandparents.
How do Jim and Jean Morgan feel toward Shirley now? "We love both girls," says Jim. "We love them very much."
Both Debra and Shirley, however, continue to struggle with the realities of being "switched at birth."
Debra still loves Polly, the mother who raised her. But she feels like she's being pulled in two different directions: "I just want to make sure everybody is going to be happy with me."
Shirley wouldn't talk to 48 Hours, but she has met her biological mom, Polly Munoz, and they are slowly getting to know each other. Her relationship, however, with the Morgan family is now strained, and Shirley and Polly have filed a lawsuit against the hospital for the emotional damage caused by this incredible mistake.
"We can't fix what happened," says Kathie. "We have to look at it and deal with it, and take the best of what we've got and go on with what's left of life."
Debra, however, hopes that she and Shirley will realize they didn't lose a family - they just gained one: "It's going to take time. I just want it to be a happy ending."