Billie Eilish Pirate Baird O’Connell was born in Los Angeles, California, on December 18, 2001. She is the daughter of actress and teacher Maggie Baird and actor Patrick O’Connell, both of whom are also musicians and work on Eilish’s tours. Eilish is of Irish and Scottish descent. She was conceived via in vitro fertilization. Her middle name, Eilish, was originally meant to be her first name, while Pirate was to have been her middle name. But after her grandfather William Baird died while her mother was pregnant, her parents decided to name her Billie, after her grandfather. She grew up in Los Angeles’s Highland Park neighborhood.

Eilish and her older brother Finneas were homeschooled by Baird, a decision their parents made to spend time with them and give them the freedom to pursue their interests. Baird taught Eilish and Finneas the basics of songwriting. Eilish said her brother and mother inspired her to get into music. Their parents encouraged the siblings to express themselves and explore whatever they wanted, including art, dancing, and acting.

Eilish started playing the ukulele at age six. She performed at talent shows and joined the Los Angeles Children’s Chorus at age eight. She wrote her first “real” song at age 11 for her mother’s songwriting class.