One art historian thinks he’s cracked the code to the mysterious “Mona Lisa”: that elusive smile was inspired by da Vinci’s gay lover.

Upon examining a recent infra-red analysis of the famous painting, art historian Silvano Vinceti has claimed that the alluring visage was based off of two people in da Vinci’s life: a rich Tuscan merchant’s wife, Lisa Gherardini, and the artist’s apprentice and alleged lover, Gian Giacomo Caprotti, known to da Vinci as “Salai,” or “Little Devil.”

Eric VANDEVILLE/Gamma-Rapho via Getty Images

In an interview with the Telegraph, Vinceti, who heads the research group National Committee for Cultural Heritage, explained that the infra-red findings prove that “the Mona Lisa is androgynous–half man and half woman.”

“You see it particularly in Mona Lisa’s nose,” he continued, “and in her forehead and her smile.”

Vinceti’s claims are based not only on the infra-red examination, but also on close study of other paintings of Salai, who lived and worked with da Vinci for the better part of twenty years.

Though Vinceti’s analysis is certainly juicy, many art experts aren’t entirely sold on the idea that the painting was inspired by the artist’s young apprentice.

“This is a mish-mash of known things, semi-known things and complete fantasy,” said Martin Kemp, professor emeritus of the history of art at Trinity College, Oxford.

“The infra-red images do nothing to support the idea that Leonardo somehow painted a blend of Lisa Gherardini and Salai.”

Kemp, who is currently at work on a new book, Mona Lisa: The People and the Painting, further adds that no one knows for sure what exactly Salai looked like.

“Giorgio Vasari (a contemporary painter and a chronicler of Renaissance artists) described him as a pretty boy with curly hair, but that was a standard type of the era. It featured in Leonardo’s work long before Salai came on the scene.”

Regardless of the theory’s truth, it is evident that the enigmatic painting will continue to baffle and intrigue experts and laypeople alike for centuries to come.