Adeline was born in Tianjin, China in 1937, to Joseph Yen, a businessman, and Ren Yong-ping, an accountant. Her Chinese name is Yen Jun-ling (???). She has four siblings and two half-siblings (disguised Christian names and real Chinese names): Lydia (b.1926 as Jun-pei), Gregory (Zi-jie), Edgar (Zi-lin), and James (b. 1934 as Zi-jun), all older than her, and two half-siblings, Franklin (b.1939) and Susan (b. 1941 as Jun-qing).

Adeline's official birthday is 30 November, but this is not her real birthday, since her father did not remember her birthday and she never knew hers, so he gave her his birthday. Two weeks after her birth, her mother died of peripheral fever and Adeline was labeled "bad luck" by the rest of her family.

In 1938, Joseph Yen married a Eurasian (half-French, half-Chinese) girl, Jeanne Virginie Prosperi, who was only seventeen years old. They children referred to her as Niang (?, another term for mother. They had two children, Franklin Yen and Susan Yen.

Niang doted upon Joseph and her son, while mistreating the rest of the family, even her own daughter and particularly Adeline. Adeline's third brother protected her from some of her stepmother's actions, although, in Falling Leaves, it appears that Adeline's only refuge from Niang is her Aunt Baba, her father's older sister. This childhood conflict, involving emotional abuse and Adeline's attempts to gain her father's affection, are detailed in her second novel, Chinese Cinderella. Throughout her childhood, she was emotionally supported by her paternal grandfather and paternal aunt. When her father became wanted by the Japanese, he left Tianjin for Shanghai. Soon afterward, her stepmother and her half brother joined him. After her father, stepmother, and half-brother disappeared, her grandmother, referred to only as Nai Nai, died.

When her father and step-mother were ready, Adeline and her three brothers and sister set off for Shanghai and moved into her father's house on Avenue Joffre. There, she was given a room of her own until her aunt and grandfather arrived, upon then when she would share with her aunt. Her aunt and grandfather arrived along with her half-sister, Susan, two months later. When Susan arrived, she did not recognise Niang, and for this, Niang beat her. Adeline protested and Niang declared that she would never forgive her.

Whenever Adeline did something, that according to Niang's book of rules, was wrong, like attend a birthday party, she was severely punished. When Adeline was elected class president, her friends came to her house of their own accord, each of them bringing presents for her. Adeline was summoned to her parents' room, where Niang beat her black and blue before commanding her to demand her friends leave. Her father then made her open the presents and then throw them in the bin.

One of Adeline's relatives once gifted her and her siblings with little ducklings. Adeline decided to name her duckling "Precious Little Treasure" (PLT for short). Adeline loved PLT with all her heart, and used to look after her with love and care, even digging up worms, PLT's favourite, for her to eat. The family owned a ferocious dog called Jackie, and one evening, when her father wanted to test out Jackie's training, he asked her brother to select a duckling. He selected Adeline's, but Jackie did not handle her well. PLT's leg was coming apart, and she did not survive the night. PLT was buried in the garden, and Adeline mourned her for a long time.

After a few unfortunate incidents with Niang, such as the class president incident, Niang became infuriated and in a burst of rage, decided to send Adeline to a boarding school.

At the age of fourteen, as her autobiographies state, Yen Jun-ling won a play-writing competition (her play Gone With the Locusts), and convinced her father to let her study in England. She completed a medical degree, and established a medical practice in California. In her free time, however, she continued to write about the tragedies that had overshadowed her life. In 1964, she married a waiter named Byron but Byron proved too violent and after their only child together was born, Adeline divorced him in 1970. Her memoir, Falling Leaves, relates her full life story. It begins by relating her emotionally deprived childhood under her stepmother's cruelty, and goes on to recount how, after her father died, her stepmother prevented his children from reading his will, until her own death two years later.

Falling Leaves sold over one million copies worldwide, prompting Mah to quit medicine and devote her time to writing. Her second novel, Chinese Cinderella, was an abridged version for children of her autobiography, and sold equally well. She has since written A Thousand Pieces of Gold, a book which looks at events under the Qin and Han dynasties through Chinese proverbs and their origins in Sima Qian's history Shiji; and Chinese Cinderella and the Secret Dragon Society, her first fiction book, based on events in World War II.