Isis Fogg was one of the several daughters of Roxana Fogg, whose grandfather had been a witness to the Wold Newton Meteorite strike. She married a rich American named Benson, and their son was Richard Henry Benson, otherwise known as pulp hero The Avenger.
Philip José Farmer discusses the Fogg family in Doc Savage: His Apocalyptic Life. The eminent pulp scholar Jess Nevins has identified Isis's husband as Alvin H. Benson and argues that Richard was actually adopted; according to Dennis Power, Richard's putative parents were actually his paternal grandparents.