The mix-up happened back in 1994 at a clinic in Cannes, where both babies were placed in the same incubator for treatment for jaundice.
A nurse then accidentally switched the girls before handing them over to their mothers.
When handed their babies, both mums voiced concern after observing their varying hair lengths, but were dismissed by staff at the hospital.
It was 10 years later, when the father of one of the girls noticed the lack of resemblance between them, that he decided to get a paternity test.
The parents were horrified to discover that they were not the biological parents of the girl, and met with the other set of parents to break the news.
While both families have known about the mix-up for the past ten years, it is only now that the girls are 20 that they have decided to take legal action.
The families are now suing the doctors and the clinic involved for over $15 million.
