Complex sentence: On June 26,1912, Dulles married Janet Avery with whom he had two sons and a daughter: their older son, John W. F. Dulles (1913--2008) was a professor of History and specialist in Brazil at the University of Texas at Austin.
Split into simpler sentences: On June 26,1912, Dulles married Janet Avery with whom he had two sons and a daughter. Their older son John W. F. Dulles (1913--2008) was a professor of history and specialist in Brazil at the University of Texas at Austin.