Zellweger was born in Katy, Texas. Her father, Emil Erich Zellweger, is from a small town in the canton of St. Gallen, Switzerland, and is a mechanical and electrical engineer who worked in the oil refining business. Her mother, Kjellfrid Irene (née Andreassen), a native of Norway, is of Norwegian, Finnish, Swedish, and possible Sami, ancestry. Kjellfrid grew up in Kirkenes and Ekkerøy, and is a nurse and midwife who moved to the United States to work as a governess for a Norwegian family in Texas. Zellweger has described herself as being raised in a family of "lazy Catholics and Episcopalians". 