Leonardo da Vinci's mother was a Chinese slave and the Mona Lisa is a portrait of her, a Hong-Kong-based historian has said.
In his forthcoming book, Leonardo Da Vinci: a Chinese Scholar Lost in Renaissance Italy, Angelo Paratico claims the relationship between da Vinci's father and his mother was frowned upon, which is why there are few records of her.
Paratico told the South China Morning Post that he is "sure up to a point that Leonardo's mother was from the Orient, but to make her an oriental Chinese, we need to use a deductive method".
He has spent years piecing together documents to make his case. Da Vinci's father is believed to have been a notary, but all that is known about her mother is that she was called Caterina.
She was moved to Vinci, about 20 miles from Florence, in 1452 to give birth. After this, there are no records of her.
Some people believe she was a local peasant, but Paratico says she was moved because having a relationship with a slave was seen as improper at the time.
"One wealthy client of Leonardo's father had a slave called Caterina. After 1452, Leonardo's date of birth, she disappeared from the documents. She was no longer working there."
Paratico believes Caterina was from China and that the Mona Lisa is a portrait of her: "During the Renaissance, countries like Italy and Spain were full of oriental slaves," he said.
"Mona Lisa is probably a portrait of his mother, as Sigmund Freud said in 1910. On the back of Mona Lisa, there is a Chinese landscape and even her face looks Chinese."
He also points to a number of other reasons da Vinci could have been Chinese: "For instance, the fact he was writing with his left hand from left to right… and he was also a vegetarian, which was not common [among Europeans]."
However, Paratico accepts the only way of solving this mystery would be by analysing DNA of relatives of the Renaissance icon who are buried in Florence.
The theory that da Vinci's mother could have been a slave from the Middle East was first put forward in 2002. Five years later, other researchers said his fingerprints suggested he was an Arab.
Art historian Vitor Teixeira said the idea da Vinci's mother was Chinese is "far-fetched", pointing out he has no facial features indicating Chinese descent.