Vladimir Putin's mysterious eldest child has broken her silence and given a rare media interview, revealing she hopes to one day cure cancer.
The Russian President has two adult daughters from his first marriage to former flight attendant Lyudmila Shkrebneva, which ended in 2013.
The eldest, Maria, is believed to have been born in Leningrad (now called St Petersburg) in 1985, with sister Katerina arriving the following year while the family was living in Germany.
However, Mr Putin has never mentioned their names publicly, and rarely comments on his family life at all, despite persistent rumours he may have fathered a third daughter.
But while Katerina has given media interviews in the past — and made headlines for her apparent passion for the quirky sport of Acrobatic Rock 'n' Roll — Maria's life has long been shrouded in mystery.
However, the blonde 33-year-old, who has been dubbed Putin's "secret daughter" by the press, has just dropped some new clues about herself during an interview with state-owned TV channel Russia 1.
During the interview it was revealed she is a co-owner and top executive at Nomeko, a new, $A894 million medical firm focused on cancer research.
Located near St Petersburg, Nomeko is said to be the biggest private investment project in healthcare in the country.
According to the BBC, the new medicine centre is due to open by 2021, and Ms Vorontsova reportedly has a 20 per cent stake along with four other owners.
It is designed to hold 20,000 patients and will be able to perform 10,000 operations annually.
WHO IS MARIA VORONTSOVA?
The Sun reports Ms Vorontsova — apparently nicknamed Masha — lives in a luxury penthouse in the Russian capital of Moscow, near the American embassy.
She is believed to be multilingual, and fluent in English, Dutch, Russian and French and is a children's endocrinologist and research assistant.
She graduated with a medical degree from the Faculty of Fundamental Medicine at Moscow State University in 2011, according to the Daily Mail, and completed an internship at the Institute of Pediatric Endocrinology at the FSBI Endocrinological Research Center — part of the Ministry of Health — in 2014.
Ms Vorontsova later completed a PhD with postgraduate research into dwarfism.
Multiple media reports have named her as the wife of wealthy Dutch businessman Jorrit Faassen and it is believed the couple have at least one child.
THE OTHER SISTER
Like her older sister, Katerina Tikhonova also spent most of her life out of the public eye — until a few years ago.
She was first identified by Reuters in 2015, as an active participant in a sport known as "acrobatic rock'n'roll" — a mix of gymnastics and dance.
Ms Tikhonova, 32, who allegedly uses her maternal grandmother's last name in a bid to remain anonymous, was also reported as heading a massive expansion of Moscow State University in 2015.
She married Russian billionaire Kirill Shamalov in 2013, although the pair have allegedly since split, and last year Ms Tikhonova made her television debut on Russia 1.
Identified as the "deputy director of the institute for mathematical research of complex systems at Moscow's State University", Ms Tikhonova spoke with reporters about advancements in technology aimed at controlling electrical impulses in the brain, BBC Monitoring reported.
In a 2015 press conference, Mr Putin stunned those present by briefly speaking about his daughters.
While he only uttered a few sentences about his family, it was one of the most revealing insights that has ever been made publicly.
"They live in Russia and have never lived anywhere other than Russia permanently,' he said, according to Whimn.
"They studied only at Russian universities. I am proud of them. They continue to study and work.
"My daughters speak three European languages fluently. One of them can even speak one or two Oriental languages. They are making their first steps and are successful."
Then, in 2017, Reuters reported Mr Putin as saying he wanted his grandchildren to have a normal childhood.
"My daughters are involved in science and in education. They don't interfere in anything, including politics. They live normally," he said.
"The thing is I don't want them to grow up like princes," he said of his grandchildren.
"I want them to be normal people. And for that they need ordinary, normal communication with other children.
"They would be immediately identified and not left in peace. It would damage the children's development. I ask you to understand me and to treat this position with understanding."