Mary Averell Knap was born in Brownsville, Jefferson County, New York, on February 21, 1836, the daughter of Thomas Loomis Knap and Mary Averell. She had four siblings: Joseph Moss, James George, Thomas Loomis, and Emmeline Eliza. Her father worked as a lead manufacturer, and he moved to Pittsburgh, Pennsylvania, in 1850, where he worked for an iron foundry. Mary lived with her mother in Brownsville and Ogdensburg, New York, throughout much of the remainder of the 19th century. She died around 1907.
Lydia Averell Hasbrouck, the daughter of Louis Hasbrouck and Emmeline Knap, lived in Ogdensburg, New York. She had five siblings: Mary, Louis, Philip, Thomas, and Louise. In 1901, she married Benjamin Kent Hough, a graduate of Cornell University's Sibley College.
Thomas Brown Whitney was born in June 1869, the son of James and Elizabeth Whitney of Philadelphia, Pennsylvania. He had three siblings: Asa, Annie, and Emma. Whitney joined the sophomore class at the College of New Jersey (now Princeton University) in the fall of 1886, and graduated in 1889 with a degree in business. After his graduation, he lived with his family in Delaware County, Pennsylvania. Lydia Averell Hasbrouck and Thomas Brown Whitney were cousins.