Tang's maternal grandfather was Wen Bingzhong (; 1862-1938), one of the 120 young boys sent by the late Qing imperial court to study in America during the Chinese Education Mission established by China's first student to graduate from an American University (Yale), Yung Wing (). Tang's grandfather was the first Chinese person to be documented in the Northampton, MA census in 1880. After his return to China, he later served as a high-level foreign service official. Tang's father was Tang Ping-yuan (), a Boxer indemnity scholarship student at the Massachusetts Institute of Technology who became one of the early civic and business leaders of post-1949 Hong Kong; he was also a leading philanthropist in education. He was widely respected for his business success and as a civic leader. Tang received many honors in his lifetime including Justice of the Peace and Order of the British Empire. He died in Hong Kong in 1971. Oscar Tang has talked about his family's roots in American education publicly and attributes his own experience and philanthropy to his family history.