information:classification, structural:summarization, structural:expansion, stylistic:tone
Ancestry and family

Kao's father Kao Chun-Hsiang (高君湘), originally from Jinshan City (now a district of Shanghai City), obtained his Juris Doctor from the University of Michigan Law School in 1925. He was a judge at the Shanghai Concession and later a professor at Soochow University (then in Shanghai) Comparative Law School of China.

His grandfather Kao Hsieh was a scholar, poet and artist, Several writers including Kao Hsü, Yao Kuang (姚光), and Kao Tseng (高增) were also Kao's close relatives.

His father's cousin was astronomer Kao Ping-tse (Kao crater is named after him). Kao's younger brother Timothy Wu Kao (高鋙) is a civil engineer and Professor Emeritus at the Catholic University of America. His research is in hydrodynamics.

Kao met his future wife Gwen May-Wan Kao (née Wong; 黃美芸) in London after graduation, when they worked together as engineers at Standard Telephones and Cables. She was British Chinese. They were married in 1959 in London, and had a son and a daughter, both of whom reside and work in Silicon Valley, California. According to Kao's autobiography, Kao was a Catholic who attended Catholic Church while his wife attended the Anglican Communion.