Last year, Trygve Wakenshaw beguiled audiences with his toddler son Phineas. Slotting into that role this time around is Beth Vyse with her real baby son Henry, as she plays fictional semi-celeb Olive Hands who is making one last desperate attempt to get back on daytime TV. Grown-up kid and journo Rebecca Wilcox appears with Esther Rantzen in a reflection on her mum's showbiz life, while Philadelphia uncle and niece magician double-act John and Claire Lenahan dabble in quick-witted and noisy conjuring in Loud and Louder.

Paul Merton and his wife Suki Webster are part of the Impro Chums, while Helen Rutter and hubbie Rob Rouse play a couple going through a tumultuous period in The Ladder. Over at the Book Festival, more married couples abound with Chris Brookmyre and Marisa Haetzman morphing into one pseudonymous person, Ambrose Parry, to pen a new crime-writing novel, while wedded pair Charlotte and Adam Guillain discuss magic, giants and jellybeans as part of the children's programme. To mark the 100th anniversary of Nelson Mandela's birth, his daughter Zindzi and great-grandchildren Zazi and Ziwelene will be on stage to discuss his 27 years in prison.

Sibling rivalries may be spilling onto the stage as identical twins and Aussie musical comics Benjamin and James Stevenson ask us to Spot the Difference, while Alexandra and Kate Donnachie discuss growing up and eating disorders in theatre work 3 Years, 1 Week and a Lemon Drizzle. Nicola and Rosie Dempsey become embittered musical comedy duo Flo & Joan, and Maddy 'n' Marina Bye do their absurdist sketch show thing in Siblings: Acting Out.

In the circus world, Ethiopian brothers Bibi and Bichu Tesfamariam return in Circus Abyssinia, and two siblings called You and Me fling themselves about in acrobatics show Sisters, while back at Charlotte Square Gardens Isabel and Imogen Greenberg discuss Greek goddess Athena. And just for the record, darkly comedic duo of Sisters: On Demand are not related. Indeed, neither of them are even female.