Stewart's musical education began with piano lessons at age 7 and classical violin at 8. During high school he gave up violin, bought his first guitar and began to sing. He studied voice at Pomona College and at the University of Illinois while majoring in Chemistry. Stewart taught Chemistry at St. Olaf College (Minnesota) for 28 years and was active in the Northfield Arts Guild, singing lead roles in summer musicals and opera workshops. He moved to Seattle in 1996 as research professor at the University of Washington, and picked up the violin again to become a fiddler.