Lucy Elizabeth Preston was born in California on 24 January 1983.

Carol Preston and Henry Wallace met at UC Berkeley in 1979 and married in 1980. Within the next three years, Carol had an affair with Benjamin Cahill, Lucy's biological father, that resulted in her birth. Until age thirty-three, Lucy believed Henry Wallace was her father and knew nothing of Cahill.

When she was young, Lucy's mother read her historical biographies for kids. Lucy enjoyed the books and planned to one day read them to her own children. Carol would also sing “I Wished on the Moon” by Bing Crosby to Lucy.

In 1990, when she was seven years old, Lucy's younger sister Amy was born. Amy is her half-sister. They share Carol Preston as a mother, but Amy's biological father is Henry Wallace, while Lucy's is Benjamin Cahill. Lucy also has a younger half-brother who shares Cahill as a father. Her brother's name and age are unknown, though it is clear he is a teenager, half Lucy's age.

Lucy Elizabeth Preston was born on 24 January 1983 at 07:46 in the morning at Stanford Hospital in Los Angeles, California (68366 Highland Street). Her father is officially listed as "unknown," and her mother's name is Carol Lynne Preston (who was born on 16 July 1961).	[ click to enlarge ]

As a child, Amy had strawberry-scented shampoo. Whenever she was afraid at night, she would crawl into Lucy’s bed. With Amy’s hair right against her nose, Lucy would dream all night of milkshakes.

In 1998, when she was fifteen, the man Lucy believed to be her father died. Amy was eight. For reasons unexplained, Henry Wallace lived two years longer in the original timeline, with his daughters, than he did in the one in which he married Elizabeth Merrick. His cause of death has not been addressed, though it is possible to have been a medical affliction, one in which his love for his family inspired to hold on two extra years. Like Carol, Henry may have had lung cancer due to smoking cigarettes.

There are conflicting accounts regarding Lucy's high school prom. In one mention, Michael Garrison, her intended or hopeful date, declined to take her, leaving Lucy upset. In the other mention, Lucy purposefully chose to skip her prom to instead attend a speech and debate tournament. Either way, she did not participate.

Lucy faced much academic pressure from her mother while in school. She stayed up late with her homework, only to find the next morning that Carol had deleted pages of her work, finding it subpar. While studying for her AP European History final, Carol played European folk music every night in an attempt to stimulate Lucy’s mind. Lucy did not like the music, but Carol justified her actions saying Lucy aced the test.

During her sophomore year of college, Lucy wanted to give up her life course pursuing an education in history. She planned to drop out of school and join a band. On her way to Carol's house, Lucy was rehearsing the speech she prepared to give and did not notice an oil slick on the road. She lost control of her car and spun into a river. The car quickly filled with water and shut down. Lucy thought it was the end for her, but was pulled out of the car by a passerby. Lucy dropped her plans to join a band and resumed her schooling. Because of the accident, she fears tight spaces and situations she cannot control.

Lucy worked for a year in the history department at The University of Chicago under a Professor McNeil.

A few years prior to 2016, Lucy was offered a professor job at a small college in Ohio. Though she considered it her dream job, her mother Carol dissuaded her from taking it, much to the disappointment of her sister Amy. Lucy remained at Stanford, following in her mother's footsteps.

Like her mother, Lucy published books on history. Two have been established in the series. One was written on John Wilkes Booth and the Lincoln Assassination. The other, A History of San Francisco 1850 - 1950, Lucy co-wrote with her mother.

Due to Henry Wallace introducing her to smoking, Carol developed lung cancer. Over time, her health declined until she was confined to bed and mostly unconscious. At the time the series begins, Carol appears very sickly and does not seem to have much time left.

By 2016, Lucy had success teaching as a history professor at Stanford University. She lectured to an impressive class size of two hundred and was enjoyed by her students. During this time, Lucy dated Jonas Lyger, department chair over the history department at Stanford (a relationship confirmed within the Pilot script but not the episode itself). Despite any romantic involvement or Lucy’s success as a teacher, Lyger did not defend Lucy when her tenure meeting was cancelled.