Manon Serrano, 18, was swapped with another baby five days after she was born at the Cannes-la-Bocca clinic in France on July 4, 1994.
The accidental switch happened when Manon was placed in a cot with another baby for treatment for jaundice.
Manon was then given back to Sophie Serrano, whose own daughter was handed to another woman.
Mrs Serrano told nurses that the child did not look like her own baby, but nurses insisted that there had been no mistake.
Manon and her family eventually discovered the maternity ward mistake after undergoing DNA tests eight years ago - but not before it tore her family apart.
This was because Manon, whose real parents are from Réunion Island, in the Indian Ocean, was dark-skinned while her 'parents' were both fair skinned.
A paternity test in 2002 proved the 'father's' suspicions and he left his wife believing she must have conceived the child with another man. Another test two years later revealed that Manon was not related to her 'mother'.
Manon says the mistake has had a huge impact on her life and left her struggling to find her own identity.
She added: "At a period of your life when you're anyway asking questions, me, I had lost my identity."
The rest of her family have also struggled to come to terms with the mistake.
Her 'mother' Mrs Serrano, from Thorenc, near Grasse, in southern France, told Le Parisien: "The sky fell on my head. I had the impression that I had lost the daughter I had brought up, but I was also seized by a terrible anguish."
Mrs Serrano, who has two other children, told the newspaper she suffered from nervous depression in the aftermath of the discovery and lost her business.
"I lost everything. We had to leave our home, I have got big debts. All my children had to consult psychologists," she admitted.
Police managed to track down the other family involved in the mix-up and the two families met.
Mrs Serrano said: "There was a mixture of trouble, joy and sadness. I fell into the arms of my biological daughter. Instinctively I loved her. But in the long term, I was able to find a place for myself."
Despite the discovery, both girls decided to stay with the families who brought them up.
Manon said: "When my mother told me of the switch, my first thought was am I going to have to leave my family? I would have felt empty without them."
Mrs Serrano is suing the clinic, which has since become a retirement home.
Maître Claude Chas, a lawyer for the clinic, admitted that an error had occurred but said the mothers should have noticed that their babies had been switched.
What a terrible story!