Nikola Broza and Veronika Cermakova have been nurtured, nursed, loved and cared for by parents who were not their biological mother and father.
The mistake may never have come to light in the Czech Republic had Nikola's purported parents, Libor Broza, 29, and his partner Jaroslava Trojanova, 25, not undergone DNA testing after jibes from friends who said the child didn't look like them.
Mr Broza, a lorry driver, said: "It was a total shock. I just cried for two hours solid and Jaroslava was inconsolable; it was just impossible to believe that this could happen. We have raised Nikola for the past ten months. She's a beautiful little girl who's always smiling and it's impossible to imagine her now living apart from us. But at the same time just 20 miles away lives our real daughter."
A fortnight after receiving the DNA tests, the couple discovered their real daughter, Veronika, was living with Jaroslava Cermakova and her husband Jan in another village.
The couples met for the first time last week and agreed that they would all gradually spend more time together before swapping Nikola and Veronika before Christmas.
"We have missed so many milestones in Veronika's life; her first teeth and her first steps. Now we are determined not to miss her first birthday and her first Christmas," said Mr Broza.
The couples are convinced that medical staff at Trebic hospital accidentally swapped their babies the day after they were born on 9 December. The children were born within 18 minutes of each other.
The mothers became suspicious after Nikola's birth weight shrank from 7.26lb to 5.72lb overnight, while Veronika's weight rose by 1.65lb - but staff on duty at the time reassured them that the babies' weights on the day they had been born had been recorded wrongly.
Mr Cermakova has photographs showing that Veronika was tagged with just a number and no name on her arm while in hospital.
Ms Trojanova said: "The whole situation is just awful. What can I say? You love your daughter, but, at the end of the day, she is not yours. Nikola is my little angel and so far I don't have any feelings for Veronika - I wish I could live with both of them."
Mr Broza said the couples now each planned to sue the hospital involved for the equivalent of 250,000.
He became suspicious after jibes from his friends pointing out that he and Ms Trojanova were both dark-haired and brown-eyed but had a blonde-haired, blue-eyed baby. He arranged for a secret DNA test which revealed that he was not Nikola's father.
When Ms Trojanova insisted he must be the father, she, too, had a DNA test done which revealed the child was not theirs.
Trebic Hospital near Brno on the Czech-Austrian border has declined to comment while an investigation was ongoing but the hospital director, Petr Mayer, this week delivered a written apology to the couples.