Sadie Sink

Sadie Elizabeth Sink was born in Brenham, Texas, on April 16, 2002. Her mother is a math teacher, and her father is a football coach. She has three older brothers and a younger sister. While her family was sports-oriented, she and her brother Mitchell were interested in performing arts, especially musical theater. They would often recreate scenes from High School Musical (2006) and watch Broadway plays and Tony Award performances. Sink said they were "so annoying and loud and constantly demanding attention" while growing up.

When Sink was seven, her mother put her and Mitchell in acting classes in Houston. Sink began acting in community theater with a production of The Best Christmas Pageant Ever in Brenham at age seven. When she was eight years old, she had a leading role in a local production of The Secret Garden, which involved "more learning lines and real practice". Her experience encouraged her to pursue a professional acting career. In 2012, Sink's family supported her and Mitchell's careers by moving to New Jersey. Sink began homeschooling while in second grade and returned to regular school after performing in The Audience (2015).