The Carles household is home to one of Britain's most extraordinary families: Meet Ellie, Georgie, Jessica and Holly - the UK's only identical quadruplets - miracles of nature, conceived against odds of 1 in 64 million. The programme follows them in the run-up to the girls' fifth birthday, sharing some of the milestones of their lives including Christmas and their first day at school. A trip to America to meet a set of teenage identical quads also gives Julie an insight into what the future holds. Narrated by Keeley Hawes. Part of the Extraordinary Families season.