In 1917 James Watson had married Violet May Lopez of Christiana, in New Haven, Connecticut. His bride had come to America in 1915; her sister Nessa, who also went to the States, married Charles Llewellyn, and they were the parents of J Bruce Llewellyn, one of the most successful African American businessmen. The families were also related to Colin Powell's family. The Watsons' children were as remarkable as the rest of the families.
Their two daughters, Barbara and Grace, became lawyers. Barbara was the first woman and the first African-American, to be U.S. Under Secretary of State for Security and Consular Affairs, and later was the U.S. ambassador to Malaysia. Grace was the Deputy Director of the Horace Mann Learning Center at the Department of Education. One son, Douglas, was the first African-American aeronautical engineer in the United States. The other son, James L Watson, followed in his father's footsteps, after serving in World War II. He became the most senior African American federal judge, and was the first Black Customs Court judge in modern times assigned to cases in the deep South.