She has two older sisters, Jenna and Jamie. While in elementary school, Cassidy became interested in show business and participated in several community theatre productions beginning at the age of 7, and as a teenager studied with an acting coach. She also starred as the protagonist, Kelli Presley, in Dimension Films remake of the 1974 film Black Christmas. in which she played Jewel Jensen, an aspiring actress looking her big break in Hollywood. Production was halted and the movie was eventually cancelled.
