David Beckham has shared an incredibly rare photo of his older sister, Lynne Georgina.MORE: Ryan Reynolds reveals what he REALLY thinks of David Beckham!The father-of-four posted two snapshots in celebration of his sibling's birthday. The first throwback showed David and Lynne as children posing with their father Ted and their younger sister Joanne. WATCH: Victoria Beckham shows fans her unusual diet at Italian health retreatThe second image is an old portrait of Lynne, showing her on her own and beaming for the camera.READ: Cruz Beckham's new girlfriend revealed as couple enjoy loved-up date in LondonMORE: Romeo Beckham divides fans as he shares unseen family photo – David Beckham reacts"Happy 50th Lynne hope you have an amazing day sis you deserve it," David captioned the post.