Mary Eustis was born in 1885, when her twin brothers were eight years old. Like her siblings, she spent time enjoying the many leisure activities available to her while not in school. As was expected, Mary was formally presented to society at age nineteen on January 5, 1904, in a lavish ball held at Copley Hall in Boston. Tragically, Mary’s mother Edith became ill on the day of the party and died just four days later. Mary Eustis married in 1908 and moved to New York.