Lydia Wangari Githinji was born on August 2, 1972, in Kijabe, Kiambu County, as the first of six children to Reuben Karobia and Ruth Njeri. In 1976, her family moved to Mai Mahiu, where her father owned land. She attended Kijabe Primary School, walking from Mai Mahiu daily due to its superior academic performance and her mother’s role as a preschool teacher nearby. She completed her primary education in 1986 and proceeded to Uthiru High School, graduating in 1990.
In 1991, Lydia began working as a casual laborer at Kijabe Printing Press. The following year, she was employed at Kijabe Medical Center, where she met her future husband, John Githinji, a colleague. While working, she pursued professional computing and data processing at Universal Group of Colleges, completing her studies in 1994. Lydia and John married that same year and were blessed with two children, Peris Munga and Samuel Murugi. She is also a grandmother to Ayana Wambui.