PHOTO: Instagram/Will Smith, Instagram/Jaden Smith

Will Smith has poked fun at his son Jaden for not having any children yet.

The actor shared an Instagram post on Saturday (July 8) to mark Jaden’s 25th birthday but took the opportunity to suggest it was time for him to become a grandfather.

The 54-year-old star — who has Trey, 30, with ex-wife Sheree Zampino, and Jaden and Willow, 20, with wife Jada Pinkett Smith — shared a black and white photo of him with his arm around his youngest son and wrote: “Happy Birthday, J-Diggy. It’s crazy that you’re 25?!

“When I was 25 I had a two-year-old… I’m just sayin’… What’s up? What you doin’ over there?

“Btw, this is my favourite picture of us.”

Jada’s mother, Adrienne Banfield Norris, mocked her son-in-law for his post.

She quipped in the comments: “He’s smarter than you [laughing face and winking emojis].”

Jada also shared a birthday tribute to her son, which featured him as a baby smiling as she kissed him, and a more recent photo on the red carpet.

She wrote: “Happy 25th birthday my sweet, sweet Jaden!”

Jaden recently revealed his mother inspired their family to use psychedelic drugs.

He told the Psychedelic Science conference in Denver: “I think it was my mom, actually, that was really the first one to make that step for the family.

“It was just her for a really, really long time and then eventually it just trickled and evolved and everybody found it in their own ways.”

Jaden didn’t specify which psychedelics he was referring to, but said they have helped him form stronger relationships with his sister and his half-brother in a “profound” way.

He said: “Siblings can argue so much and fight so much, and lord knows me and my siblings have done so much of that in the past.

“But the level of love and empathy that I can feel for them inside of the [psychedelic] experiences and outside of the experiences has been something that’s profound and beautiful.”

He added about how drug use has helped them resolve differences: “It will actually help us to open up our minds, to get out of the old ways of thinking that got us into lots of these arguments, and open it up so that it just releases and makes room for you to work it out and massage it out until it’s completely gone.”