Mary was born in Melbourne in 1938, one of a family of seven girls and one boy. She married Maurice Sexton in 1957 and had two daughters, Alison and Luise. They moved to Canberra in May 1972 where Mary was able to pursue her interests in women and Indigenous people through her tertiary studies at the ANU.
Mary joined the Women,' Electoral Lobby (WEL) in June of that year, and has been a member ever since. In 1992 she was awarded the WEL, Real Australia Day Award, for her contribution to Aboriginal and women's affairs - in particular for her ' work behind the scenes in the early 1980's to get the Aboriginal Women's Task Force off the ground'.
Other highlights of her work with women were the establishment of the Pamela Denoon Lecture and working with Edna Ryan on the impact of enterprise bargaining on women.
In 1975 Mary re entered the paid workforce. During her 24 years in the Commonwealth Public Service she worked in a number of areas; many of them concerned with social policy issues. The highlights were her eight years in the Office of the Status of Women, four of them working on the Aboriginal Women's Task Force. In the latter stages of her career she worked in Injury Prevention where her efforts were recognised by the Australian Injury Prevention Network with an Outstanding Contribution Award in 1999.
She is a Trustee for the Pamela Denoon Trust and a member of Women's History Month Committee.