The Mona Lisa is widely known as one of the most famous, most written about and most parodied works of art in the world.

Painted by the Italian artist Leonardo da Vinci circa 1503-1519, the original portrait of Lisa Gherardinithe, the wife of Francesco del Giocondo, hangs in the Louvre Museum in Paris. And until now, every other interpretation of the work has said to have been fraudulent.Isleworth Mona Lisa

But according to ABC News, the Mona Lisa is said to have a legitimate older sister. Known as the Isleworth Mona Lisa, the work is said to have been painted 10 years earlier and was discovered shortly before World War I by English art collector Hugh Blaker.

Blaker reportedly purchased it from the noble family to which it had previously belonged, but then moved the painting to his studio in Isleworth, England, giving it its iconic name.

Slightly larger than the one that hangs in the Louvre, the Islesworth Mona Lisa is framed by two columns and apparently shows a younger version of Lisa del Giocondo, the woman who posed for the portraits. The more youthful portrayal of Giocondo gives legitimacy to the theory that it was painted earlier and is in fact real.

While some might question the facts that give the theory its apparent validity, an clear answer to whether the Isleworth Mona Lisa is real has not been available until now.

The Mona Lisa Foundation, which was set up to conduct research into the work, has reportedly announced that it has "historical, comparative and scientific evidence" that will prove once and for all that the painting is an authentic de Vinci.

Professor Carlo Pedretti of the Armand Hammer Center for Leonardo Studies at the University of California in Los Angeles and professor Alessandro Vezzosi, director of the Leonardo da Vinci Museum in Vinci, Italy have reportedly taken part in confirming the claim that the painting is real.

But while the evidence itself has not yet been revealed, the Isleworth Mona Lisa will remain just another parody in the shadow of its fraternal twin.