Little sister syndrome: Pippa Middleton, Serena Williams, and Dannii Minogue

Little sister syndrome: Pippa Middleton, Serena Williams, and Dannii Minogue

3:19 PM on 16th May 2011

Taking the lead: Pippa Middleton has been stealing the limelight from her previously more famous sister, Kate, the Duchess of Cambridge

Taking the lead: Pippa Middleton has been stealing the limelight from her previously more famous sister, Kate, the Duchess of Cambridge

All eyes on Pippa: It was Kate

All eyes on Pippa: It was Kate”s big day, but Pippa who became an internet sensation for her figure-hugging dress

Sister act: Dannii Minogue, right, now has a higher profile in the UK than sister Kylie thanks to her role on The X Factor and modelling for Marks & Spencer

Sister act: Dannii Minogue, right, now has a higher profile in the UK than sister Kylie thanks to her role on The X Factor and modelling for Marks & Spencer

Anything you can do, I can do better: Serena Wlliams, left, has played Venus at her own game and won (pictured here after winning the 2009 Wimbledon final)

Anything you can do, I can do better: Serena Wlliams, left, has played Venus at her own game and won (pictured here after winning the 2009 Wimbledon final)

Role model: Sasha Slater, left, followed big sister Lydia into a career in journalism

Role model: Sasha Slater, left, followed big sister Lydia into a career in journalism