The oldest daughter of actors and Denise Richards, she was born in Los Angeles, California.
Her parents met while filming the 2000 movie Good Advice and became romantically involved a year later on the set of Spin City. They married in the summer of 2002 and divorced when Sam was two years old.
Her mother starred in the E! reality series Denise Richards: It's Complicated.
She has a younger sister named Lola Rose Sheen, an adopted sister named Eloise Joni Richards, a half-sister named Cassandra Jade Estevez, and twin half-brothers named Bob and Max Sheen.
In 2011, her father, who was then starring on the CBS series Two and a Half Men, was replaced by Ashton Kutcher.