Complex sentence: Eaton was born in 1875 to John and Margaret (née Herbison) Eaton and related to the department store founder as they shared the same grandfather John Eaton Sr (1784--1834).
Split into simpler sentences: Eaton was born in 1875 to John and Margaret (née Herbison) Eaton. He was related to the department store founder, as they shared the same grandfather, John Eaton Sr (1784--1834).