Gigi Hadid wishes sister Alana birthday with an adorable photo

Gigi Hadid shared the sweetest moment with her sister Alana Hadid.

The star showed off her slim figure in an elegant white dress with strategic cut-outs as she celebrated her sister Alana Hadid's 40th toga-themed birthday party.

The event was toga-themed, with the blonde supermodel's sisters Alana and Marielle rocking similar variations on Roman and Greek gowns in honour of the occasion.

Gigi wore her signature blonde locks in a tight knot and her toga ensemble with a thin silver necklace and dainty pearl earrings.

The Never Have I Ever star wore simple cream coloured ballet flats to complete the look.

'Celebrating our sister!' the Los Angeles–born beauty captioned the family photo that she shared on Instagram for her millions of followers.

While Bella Hadid is arguably the most famous of Gigi's siblings, all in all, there are five Hadid children: Gigi, Bella, Marielle, Alana and Anwar.

Marielle and Alana are the eldest Hadids and come from Mohamed Hadid's first marriage to Mary Butler back in the early 90s.

The birthday girl is the second eldest Hadid child, having been born on July 27, 1985.

Alana lives in New York City where she makes a living as a fashion designer unlike her model siblings.