As a young man in Paris in the 1850s, the French painter Édouard Manet began a turbulent affair with Suzanne Leenhoff, his alluring Dutch piano teacher. Things soon got complicated: Leenhoff was also sleeping with Manet’s father, Auguste. A baby, Leon Leenhoff, was born to Suzanne in 1852, out of wedlock. The boy appears in many of Manet’s paintings, such as Boy Carrying a Sword (1855). In 1862, Manet and Leenhoff married, but the looming question was never answered: Who was Leon’s father—Édouard or Auguste? On the 150th anniversary of the artist’s death, the Gardner explores his complex family relationships, promising to shed new light on “the father of modernism,” if not on the father of Leon. —Elena Clavarino