Billie Faiers and Sam Faiers were born in the same year

Sam Faiers and Billie Faiers are set to star together in the latest series of The Mummy Diaries. 

The sisters, who rose to fame on The Only Way Is Essex, are now both mums of two. 

The first episode will see Sam, who is mum to son Paul and newborn daughter Rosie, settling into her new house with partner Paul Knightley. 

Meanwhile Billie, who has daughter Nelly, three, and Arthur, one, and fiance Greg Shepherd are organising their wedding day.

Sam Faiers and Billie Faiers were born 11 months apart

The two are clearly close.

But as well as sharing a cherished sister bond, they’re also very close in age. 

So who is the oldest and how big is the age gap between the pair? 

It turns out they were actually born in the same year - 1990. 

Billie Faiers documented her pregnancy and birth in the last series of The Mummy Diaries

Billie is the older of the two siblings, and is 28 years old. 

She was born 15 January 1990. 

Meanwhile Sam was born 31 December 1990. 

She’s 11 months younger, and is 27. 

It's caused people to question if they're 'Irish twins'.