Then on Friday, her 20-year-old son, Adam, fatally shot Lanza in her 36 Yogalanda St. residence in Newtown and proceeded to kill six adults and 20 children at Sandy Hook Elementary School before killing himself, police say.
There are conflicting reports as to whether Lanza, 52, was a kindergarten teacher or teacher's aide at the school.
"They seemed very normal. I knew the mom; she was a nice person," said a Yogalanda Street neighbor who did not want her name published. "I don't know for sure if the sons lived there. Once they go to high school, you don't see them waiting for the bus anymore. I remember (Adam) as a little kid. I don't know if I'd recognize him anymore."
Nicholas Germak, who resides five homes away from Lanza's property, said he has lived in the neighborhood nine years. "Not once did we have any contact with the kids," he said. "I had no clue these kids were even living at the house, but the houses are pretty far apart. Five houses away is like two blocks."
Two of his children formerly attended Sandy Hook, Germak said. "It's a horrible thing - tough night," he said.
The Lanza house, built in 1998, sits on more than three acres with $12,067 in property taxes. The quiet, upscale neighborhood holds large homes with sprawling lawns.
Court records show Lanza had no criminal history and was divorced from her husband, Peter John Lanza, in 2009. At the time, she continued to live at their Newtown home, built in 1998, and Peter Lanza had moved into an apartment in Stamford.
One or both of them had participated in a parenting education program, according to Superior Court records, which also show proceedings were held for custody of a minor child.
Their older son, Ryan, 24, initially was misidentified as the shooter. Ryan Lanza is being questioned by authorities but has not been charged with any crime.
A state court database shows no records of either Lanza brother having a criminal past or any pending cases.
Nancy and Peter Lanza were married in Kingston, N.H., in 1981 and according to birth records, Adam was born in April 22, 1992. Nancy Lanza's maiden name was Champion. She was the sister of James Champion, a Kingston police officer and her stepfather, Paul Hanson, was a former teacher and principal in Epsom, N.H., as well as a thoroughbred horse owner, according to SalemNews.com in Massachusetts.
Peter Lanza now lives in Stamford, Conn., according to reports, and is remarried.