, with the cast of
Runaways. Gardner was born in Sacramento, California. She attended
Sacramento Country Day School from kindergarten to eighth grade. She took part in many of her middle school's productions. In 2011, she took online schooling when she moved to
Los Angeles, but then chose to take the
California High School Proficiency Exam when she was allowed to, in October 2011. Her desire to act was due to the 2001
Sean Penn film
I Am Sam; "In the movie,
Dakota Fanning's dad has
autism, and I have a brother with autism and I remember watching that as a young girl and relating to her character and being affected by that," Gardner explains. "That’s what made me want to get into this industry and make things that can affect people and that people can relate to." She has a
black belt in
taekwondo, and also took up boxing and
nunchucks. Gardner initially lived with her mother to pursue acting full-time. Gardner lived with her mother for the first year; however, once she started to be more successful and able to handle herself, she moved into her own apartment and began to live on her own. After appearing on the
Disney Channel series
Lab Rats, she took a year off from acting to work on modeling. When she became absorbed in modeling, she was going to stop acting, but then heard about the audition for
Glee. She has modeled for
Kohl's, Love Culture, HP,
Hollister, LF, and
Famous Footwear. The movie helped Gardner to establish herself in Hollywood. In February 2017, it was announced that Gardner would star as
Karolina Dean in
Marvel's
Runaways (2017), a
Hulu original series. She has received wide recognition for her portrayal of the LGBTQ hero. ==Personal life==