John remembered his son in a touching social media post on Wednesday. [Courtesy]

John Travolta has paid tribute to his late son Jett on what would have been his 29th birthday. The Grease star, who shared his son with late wife Kelly Preston, remembered Jett in a touching social media post on Wednesday.

Jett, who was just sixteen when he passed away, died after hitting his head on the side of a bathtub after suffering a seizure while on holiday with his family in the Bahamas. To mark his son’s special day, grieving dad John shared a wholesome photo of the father-son duo where the actor gazed lovingly at his teenage boy.

Alongside the heartbreaking throwback snap, John penned: “Happy birthday my beautiful Jetty. I love you.” John’s daughter Ella, 21, also paid tribute to her older brother as she posted a precious black and white snap of the siblings sharing a special moment together as kids.

She captioned the wholesome shot: “I love you Jetty. Happy Birthday.” John’s late wife Kelly, who sadly passed away in July 2020 after a tough breast cancer battle, previously revealed that Jett suffered from seizures due to autism.

During an episode of The Doctors after her son’s tragic death, the mum-of-two explained: “Jett was autistic. He had seizures and when he was very young, he had Kawasaki Syndrome.” During her appearance on the show, Kelly also shared her opinion that chemicals in food and the environment cause children to develop autism.

John’s late wife explained at the time: “I strongly believe as a mother, as does my husband, that there are certain contributing factors that lead to autism and some of it is very much the chemicals in our environment and in our food." Jett was the eldest of three children, having a sister, Ella Bleu, and brother, Benjamin, who was born after his older sibling's death.

In 2009, John and Kelly set up the Jett Travolta Foundation, a charity that funds assistance and support for children with special needs.

Kelly with children Ella and Jett [Reuters]