Rooney Mara and Joaquin Phoenix publicly confirmed the birth of their son, River, in an op-ed published on Monday, November 2.Mara, 35, and Phoenix, 46, whose baby news made headlines in September, spoke out against the migrant children crisis in the United States in a joint article for People.“Last week, we learned that the parents of 545 children separated at the border by immigration officers have not yet been found.