Mack was born in Germany but moved with her family to Long Beach, California, when she was 2. (29 July 1982, Preetz, Germany)

She began acting at 4 with print work and commercials, and began studying at The Young Actors Space in Los Angeles when she was 7. She is still currently attending classes there in improvisation and scene study. Before joining the cast of "Smallville" (2001), Allison starred in the short-lived and sorely under-rated Fox television comedy "Opposite Sex" (2000). Prior to that, she was a regular on "Hiller and Diller" (1997), working alongside great talents such as Richard Lewis, Kevin Nealon, and Eugene Levy. Allison has also guest-starred in the WB family drama "7th Heaven" (1996) as a teenager caught up in the "cutting" trend.