The artist Susan Dorothea White has interpreted the masculine proportions of Mona Lisa's cranial architecture in her anatomical artworks Anatomy of a Smile: Mona's Bones (2002) and Mona Masticating (2006). Lillian Schwartz of Bell Labs suggests that the Mona Lisa is actually a self-portrait. She supports this theory with the results of a digital analysis of the facial features of the woman in the painting and those of the famous Portrait of a Man in Red Chalk.

Leonardo da Vinci was gender variant. We know that much. A recent analysis of the Monna Vanna indicates that the model was a man (or someone assigned male), most likely his assistant Milanese Salaì. (Look at the arm and the hands.)To be direct about this: This looks like the drawing of a feminine man with two silicon breasts added to the chest. Michelangelo's women would sometimes look a bit similar.Both Michelangelo and da Vinci were attracted to men.I have never seen final proof of the theory that the Monal Lisa was a self portrait. It was more likely a portrait of Francesco del Giocondo's wife. But the idea is intriguing.From the wikipedia:Leonardo has also done the exact opposite, presenting men in female form, as in his drawing of John the Baptist, Angelo Incarnato:Another painting by Leonardo; St John the Baptist with the Attributes of Bacchus, presents another feminine presentation of the saint:In other words: transgender exploration is nothing new.