Born and raised in Jackson, Wyoming, Stiegler is the daughter of Olympic champion Josef "Pepi" Stiegler of Austria. She began skiing at age two and racing at six at Jackson Hole. Junior Olympic and Nor-Am success while still a teenager led to a berth on the U.S. Ski Team; she made her World Cup debut at age 17 in December 2002 at a slalom in Lenzerheide, Switzerland, where she finished a remarkable eleventh. At the 2003 Junior World Championships in France, she won bronze medals in slalom and combined, to which she added a tenth-place finish in combined at the "grown-up" World Championships that year in St. Moritz, Switzerland.