Bartlett was born in Plymouth, Massachusetts, to William Bartlett and Susan Thacher. His father was a descendant of Mayflower Pilgrims Love Brewster, a founder of the town of Bridgewater, Massachusetts. Elder William Brewster, the Pilgrim colonist leader and spiritual elder of the Plymouth Colony.
And John Alden, who was hired as a cooper in Southampton, England, just before the voyage to America and who along with the Brewsters were signers of the Mayflower Compact. His mother was a direct descendant of Anthony and Elizabeth Thacher who were the sole survivors of a terrible shipwreck on August 14, 1635 in which twenty one passengers including their four children were drowned.