McAvoy was born on 2 August 1982 in
Glasgow, to bus-driver-turned-builder James McAvoy and psychiatric nurse Elizabeth (
née Johnstone; who died 2018). She was brought up as a
Roman Catholic. Her parents separated when she was four and divorced when she was eight. McAvoy's mother suffered from poor health throughout her childhood. McAvoy is the younger sister of Hollywood actor
James McAvoy and has a younger half-brother named Donald. Her brother James confirmed in an interview with
The Guardian that both of their parents were deceased. She attended the Catholic
St Thomas Aquinas Secondary School in
Jordanhill. In 2022, she gave birth to her first child, Jamie Clement, her water breaking on the set of
Two Doors Down. ==Career==