Sophie Serrano was devastated when she learned that her daughter Manon wasn't really her daughter.
Incredibly, she'd been given the wrong child.
But even more shockingly, the Serrano from Grasse, France family met up, and then took the heartbreaking decision to remain strangers to one another.
"After we all met it was hard for us to go back to our normal lives," Sophie revealed on the latest episode of TLC's Separated at Birth.
"It was the same for them. So in order to go back to our normal lives, we don't see each other any more."
The terrible mix-up began in the hospital on the day Manon was born.
"After putting two babies in the cot, the childcare assistant who was sick and had been drinking swapped the babies and brought me another family's baby in my baby's clothes," Sophie told MailOnline.
Eighteen at the time her daughter was born, Sophie had queried if the child was hers - she looked different to what she'd remembered, with darker skin.
Sophie was told that that was the result of exposure to the UV lights.
"I had hardly seen her the first few days. I was tired, the families were visiting and you feel powerless too with all the doctors and nurses. You do what you are told."
Sophie's then-partner never believed Manon was his. Assuming Sophie had cheated, he left her and refused to pay child support.
So a DNA test was initiated.
It was thanks to this test that Sophie made the shocking discovery that Manon wasn't her biological daughter - and that she had another daughter out there somewhere.
Despite the heartbreaking mix-up, Sophie insists that the discovery never changed how she felt about Manon.
"Her place in my heart is untouchable," she said.
"We have a close relationship, a bond of love and trust, our relationship has been strengthened."
However, it was extremely difficult to break the news to Manon, who was just ten years old at the time.
"It was like I'd been knocked down," Sophie said. "I knew from the moment I told her the news I would change her life forever. I was scared, very scared. I worried that when the other parents found out about her, they'd want to take her back."
Manon was devastated when Sophie first broke the news to her.
"I had been with her for almost ten years of my life. I didn't want to be taken away from her," she said.
Eventually, Sophie and Manon learned that the other family were still living in the same region of France. But meeting for the first time was heart-wrenching.
"We arrived," Sophie recalled. "My biological daughter ran towards me and jumped into my arms. I was overwhelmed because the last time I had held her in my arms was ten years ago."
"I really saw the similarities in her eyes, her hair, her face, her smile and the similarities with her father, my ex partner. It was really moving. I didn't want to let her go."
Manon also noticed similarities between herself and her biological dad.
"I had his nose, the eye colour of both my biological parents. It was al these small facial details, the reasons my hair was like this," Manon said.
"In some ways I was happy to see myself in someone else physically speaking."
However she said it was also 'distressing' as "they were strangers I didn't feel I belonged to them because what makes a family is love."
While the families (who've been compensated) initially met quite often, they gradually reduced their visits and eventually made the tough decision that it would be easier to move on if they stayed out of one another's lives.
"It was too difficult for us meeting up like that," Sophie said. "I have no regrets."
