Wendy Crewson was raised in Winnipeg, Manitoba, Canada. She attended Westwood Collegiate and was first exposed to acting when she performed in The Boy Friend in grade 10.
Graduated from Queen's University in Kingston, Ontario with a BA in Drama in 1977. Switched from English. Daughter Maggie was born in 1989 and son John (Jack) Branton Murphy in 1992. Wendy and actor husband Michael Murphy have two children, Jack Murphy (b.1992) and Maggie Murphy (b. 1989), both of whom co-starred in the movie Sleeping Dogs Lie with their parents. Wendy Crewson is good friends with actor Harrison Ford.