Larisa was born in Santa Clara County, California, to Lorraine (Allen), a nurse, and Roman Oleynik, an anesthesiologist. Her father is of Ukrainian and Slovak descent. Larisas big break came when she was eight. She had gotten the part of young Cosette in a production of Les Misérables. Her costar was Rider Strong, playing Gavroche. The two would be reunited when Larisa guested on Riders sitcom, Boy Meets World (1993). Larisas most well known roles are Bianca in 10 Things I Hate About You (1999), and Alex in The Secret World of Alex Mack (1994).