Katie Cassidy -- daughter of '70s teen idol David Cassidy -- discovered her own musical talent at an early age, singing along with the radio as a young girl and moving on to singing lessons at age 12. Along with taking piano and guitar lessons as well, Cassidy also performed in local musical theater productions. The Los Angeles-based teen began working with pop producer Joel Diamond, and in summer 2004 she released her first single, an update on her father's bubblegum classic "I Think I Love You." That fall, Cassidy also appeared in a VH1 series about the history of teen music and continued her studies. ~ Heather Phares