Cheaper by the Dozen

Cheaper by the Dozen is a semi-autobiographical novel written by Frank Bunker Gilbreth, Jr. and Ernestine Gilbreth Carey, published in 1948. The novel recounts the authors' childhood lives growing up in a household of 12 kids. The bestselling book was later adapted into a feature film by Twentieth Century Fox in 1950 and followed up by the sequel, Belles on Their Toes (1950), which was adapted as a 1952 film.

Question: is cheaper by the dozen a true story
Answer: yes