Shaun Cassidy shared a sweet photo of mom Shirley Jones with her birthday cake in celebration of the star's 91st birthday on March 31.

Shaun Cassidy, Shirley Jones, David Cassidy, Ryan Cassidy and Patrick Cassidy in 2009 Related: Shirley Jones' Son Ryan Cassidy Releases Children's Book on Day with James Cagney: 'He Was Bigger Than ...

an Oscar win and her hit TV series 'The Partridge Family' Oh, what a beautiful day — because Shirley Jones is 91! Jones’ son Shaun ... David Cassidy (she married his father Jack Cassidy ...

Oh, what a beautiful day — because Shirley Jones is 91! Jones’ son Shaun Cassidy shared a sweet birthday ... Howard and Glenn Ford. Jones and Jack, who also share sons Patrick and Ryan ...

David was born to Jack Cassidy and his first wife, Evelyn Ward, in 1950. Shaun was born to Jack and his second wife, Shirley Jones, in 1958. "There were no better nights than when David came to ...

David was born to Jack Cassidy and his first wife, Evelyn Ward, in 1950. Shaun was born to Jack and his second wife, Shirley Jones, in 1958. "There were no better nights than when David came to sleep ...

Jeff Hochberg/Getty David Cassidy performing live on Oct. 3, 1973, in London Born in New York City in 1950, Cassidy grew up surrounded by show business. His father, Jack Cassidy, was a well-known ...