Rodarte designers Laura, left, and Kate Mulleavy at the Huntington Library, Art Collections and Botanical Gardens in San Marino, Calif.
Kate and Laura Mulleavy, the sisters behind the fashion brand Rodarte, are strolling the grounds of the Huntington Library, Art Collections and Botanical Gardens in San Marino, Calif., finishing each other's sentences and often speaking in unison. They discuss the delicacies of a certain Victorian rose. They agree that the stem of an antique lightbulb inside the library reminds them of a carousel. They recall childhood trips to the Huntington estate to visit their maternal grandmother, who worked there as a docent.
What they don't talk about is fashion. Kate, 33, and Laura, 31, are dressed down in jeans and matching...
