Daisy was born over two hundred years ago in the Commonwealth. She had a husband who was killed during the Sino-American War but because of classified information she never found out where he died.
Due to the radiation that was given off after the bombs dropped, her body was slowly transformed into a ghoul. She now resides in Goodneighbor, peddling her wares from her own store Daisy's Discounts. She appears to have a darker side looking for revenge, according to a terminal entry in the Memory Den.
After clearing out the Boston Public Library for her, she will comment and thank you whenever she sees you.
Daisy says she "looks pretty good for 220 years old," suggesting that she was a 10-year-old girl when the bombs fell 210 years before the events of Fallout 4. However, she admits it's more likely 270. However, this would suggest that she was a 60-year-old woman when the bombs fell, yet she appears in Fallout 4 to be in the prime of her youth.