 Bettwy was the son of André Bettwy (1867-1951) and Mary Billand (1863-1939), natives of Alsace who immigrated to the United States and settled in Altoona, Pennsylvania.Bettwy had two sons, Andrew Leo Bettwy (1920-2004), Arizona State Land Commissioner (1970-1978) and William Frederick Bettwy (1918-2005) of Pine Bluff, Arkansas, the first commercial pilot to land at Washington Dulles Airport.His grandson was Andrew Wilson Bettwy, the second Chief Hearing Officer of the Arizona Corporation Commission (1975-1979) and renowned utility rate legal expert in Arizona, Nevada and California.