Mạnh-Thu was born on July 21st, 1954. Mạnh-Thu's father was Liêu and her mother was Chúc Ngô. Her paternal grandparents were Lê and Tuyên Ngô. She had a brother and three sisters, named Mẫn, Mai-Hương, Mộng-Thủy and Minh-Châu. She is the third oldest of the five children. She has two half-sisters named My-Dương and Kiều-Oanh.