When the parents brought their newborns home, questions were raised over their children's looks, but nothing more was thought about it until one of the girls - Irina Belyaeva - was 12.
Her dad, Alexei, accused his wife Yulia of cheating on him and demanded a paternity test for their daughter.
The incredible results revealed that the girl wasn't biologically theirs – then further investigations showed that Anna Iskanderov, who was raised by Yelena and Naimat, was.
The parents now 'share' their daughters, although they have struggled with how differently their biological children have been raised. The Belyaevs are Christians while the Iskanderovs are Muslim.
The mix-up began when Yulia, 32, and Alexei, from Kopeisk in the Urals, were expecting their first baby in 1998, The Siberian Times reported.
Naimat , 36, an ethnic Tajik, married the then 16-year-old Yelena, and their baby was due on the same date.
The two women gave birth to their daughters on December 17. Yulia gave birth at 1.30am to a girl she called Irina, 15 minutes after Yelena welcomed her baby daughter, called Anna.
In hospital it is thought that the girls were switched and wrongly tagged as the other. Yulia's husband Alexei questioned why their daughter had such dark hair and features, when they were pale and blond, but his wife thought she had picked it up from other family traits.
The problems began when Alexei became suspicious of Irina, and accused Yulia of cheating on him. He accused Irina of not being his biological daughter, and demanded a divorce in 2007.
She insisted she had not and, when Alexei refused to financially support Irina, Yulia took him to court, and a DNA test to confirm paternity was arranged in 2010. It was then that tests revealed that neither of Irina's parents were biologically related to her - she had been swapped at birth.
After contacting the Prosecutor's Office in 2011, an investigator tracked down Naimat and, with him, Yulia's biological daughter, called Anna.
Anna's dad Naimat had been blissfully unaware there was an problem and initially refused to meet with the other family, but relented and met his biological daughter, who he described as his 'mirror image'.
Three years on and the families now 'share' their 14-year-old daughters, with Anna and Irina calling both parents 'Mama' and 'Papa'.
The cultural differences between the two families meant that it would be impossible for the girls to simply swap back to their biological families.
They have decided to continue raising each other's biological daughters primarily as their own responsibility, but celebrate holidays and birthdays with each other. The families decided to prosecute the hospital for negligence.
They were awarded six million roubles each (around $200,000), but they are still waiting payment because the maternity hospital has no money.