Throughout her career as a competitive gymnast, Simone has received support from her parents, Ronald and Nellie Biles. Ronald is Simone's maternal grandfather, and Nellie is his wife, and the couple adopted Simone and her sister, Adria in 2003. At the time, Simone and Adria had been in and out of foster care for several years. Simone's other siblings, Tevin and Ashley, were adopted by Ronald's sister.

As Simone explained during Dancing With the Stars in 2017, her biological mother often struggled with alcohol and drug abuse and was in and out of jail as a result.

"I never had mom to run to. I do remember always being hungry and afraid," she said.

Ronald insisted that she call him "dad" and Nellie "mom" following the adoption, and Simone happily complied with the request.

"My parents saved me," the gymnast said. "They’ve set huge examples of how to treat other people, and they’ve been there to support me since day one. There’s nothing I could say to them to thank them enough."

Ronald and Nellie made headlines in 2016 when they were in Rio to support Simone during the Olympics. In Tokyo, they weren't allowed to attend because of COVID, but the couple remain a huge part of Simone's support structure.