Mary Julia Whalen is the daughter of Mary Suzanne McGrath and Martin Joseph Whalen (Sr.). She was born in 1961 in Illinois.

In 1982, she married Michael Peter Hannon in Illinois. He is the son of William Patrick Hannon and Mary Boniface Murphy. He was born in 1962 in Illinois.

Children of Mary Julia Whalen and Michael Peter Hannon:

1. Kaitin McGrath Hannon was born in 1982.
2. Kevin Whalen Hannon was born in 1985.
3. Peter Michael Hannon was born in 1989.
4. Mary Colleen Hannon was born in 1992.