Jessica Chastain is of French, Dutch, English, Scots-Irish/Northern Irish, Scottish, Welsh, and Irish descent.
Jessica Chastain was born on March 24, 1977, in Sacramento, California, the United States, to Jerri Renee Hastey (née Chastain) and rock musician Michael Monasterio, and was raised in a middle-class household in a northern California suburb. Her parents were teenagers when she was born. She has two sisters and two brothers. Her sister Juliet died by suicide in 2003 following years of drug abuse.
Chastain was raised by her mother and stepfather. Her mother, Jerri Chastain, is a vegan chef whose family is originally from Kansas, and her stepfather is a fireman. She is estranged from her biological father and his name is not on her birth certificate. She has said that her stepfather was the first person to make her feel secure.
She shares a close bond with her maternal grandmother, Marilyn, whom she credits as someone who "always believed in me". It was her grandmother, who sparked her passion for acting by taking her, aged seven, to see David Cassidy in Joseph and the Amazing Technicolor Dreamcoat. "There was a 10-year-old girl on stage as the narrator," she recalled later. "And as soon as I saw the girl… I just knew it was what I was going to do."