Who is Mrs. Lisbon from The Virgin Suicides and what is their importance?

Mrs. Lisbon is the mother of the Lisbon girls. Her age and first name are never revealed, but she's probably in her late forties or early fifties. Physically, Mrs. Lisbon does not look like her daughters at all, and nothing in her appearance would lead an observer to associate her with her children. Her heavy body type, gray hair and her glasses indeed make it hard to imagine how she could have been the mold for the nice girls that she is raising. Her housekeeping habits are average at best and her motherly love is never expressed except negatively, through the rules she imposes. Mrs. Lisbon has little interaction with the suburban community she lives in and almost never reaches outside the confines of the family's home.