Rob Lowe, 61, fans go ‘bonkers’ over surprise detail in shirt-free photo with mini-me son, 29

Rob Lowe fans went nuts over a new eye-popping photo the ’80s hunk shared to Instagram on Tuesday.

The 61-year-old St Elmo’s Fire actor and former Brat Packer had on shorts as he stood next to his look-alike 29-year-old son John Owen while in a gym.

It was surprising what great shape both of the actors – who costarred for two seasons on the show Unstable – were in as they looked tanned and toned.

And it was cute that both men were flexing their arm muscles and sucking in their tummies for the camera while wearing gold necklaces.

But there was a surprising detail that caught followers off guard.

Can you guess what it is?

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Rob Lowe fans went nuts over a new eye-popping photo the ’80s hunk shared to Instagram on Tuesday

The 61-year-old St Elmo’s Fire actor and former Brat Pack star had on shorts as he stood next to his look-alike 29-year-old son John Owen while in a gym

It was a large new tattoo on Rob’s arm.

Fans were shocked that Rob had a massive tattoo on his arm that does not seem to go with his clean public image.

‘I am going bonkers, Robby with a monster tat, oh hell no,’ said one fan.

Some fans found it sexy: ‘Rob just got a little hotter now that I know he has that nice tat.’ Another said: ‘It’s hot like Johnny Depp hot.’

Then there was this: ‘He looks like a foxy sailor from Boston with that ink scrawl.’ 

The tattoo is not the same one he showed off to Ellen DeGeneres on her talk show several years ago; that one is on his other arm.

The big, dark one seems to be new. He did not have it when he posed shirtless on the cover of Vanity Fair in 2018. And he did not display the tattoo when he was seen on a boat in 2024. But he did have it in April of this year.

Fans also liked his son’s mark that featured a long-stemmed wine glass: ‘Tat like dad but smaller, how cute.’ 

Rob seemed to be having fun sharing the rare shirt-free photo: ‘Lowe family tradition: self indulgent shirtless gym photos,’ the star joked. 

But there was a surprising detail that caught followers off guard. Can you guess what it is? It was a new large tattoo on Rob’s arm

Fans also liked his son’s mark that featured a long-stemmed wine glass: ‘Tat like dad but smaller, how cute’

Lowe’s older son Matthew, 32, took a jab at his brother as he said, ‘Why does it look like you photoshopped your head on @johnnylowe.’

Rob shares his two sons with his wife of many decades, jewelry designer Sheryl Berkoff.

Rob is staying busy by hosting the podcast Literally! With Rob Lowe, where he regularly welcomes A-list guests including Adam Scott, Jason Isaac, and Kristin Davis. He is also the face of the Tubi game show The Floor. 

Earlier this month Lowe shared vivid memories of his grandmother Mim’s battle with breast cancer.

The actor, known for his role in 9-1-1: Lone Star’ shared a close bond with his grandmother during his childhood, and has said his grandmom’s health fight became a pivotal experience that would shape his life and the way he approaches cancer awareness today.

He told People: ‘My memory of it is like it happened yesterday because of this sort of uproar it caused in our family. In those days, the odds were not good. I 100 percent remember our family feeling lost, wishing that there was more that could be done.’

Rob shares his two sons with his wife of many decades, jewelry designer Sheryl Berkoff. Seen in April in Los Angeles 

Rob affectionately refers to his grandmother as ‘my beloved,’ and recounts the profound impact her illness had on their family.

As Mim’s condition worsened, doctors told her to ‘get her affairs in order’ in a grim diagnosis that devastated the family.

But just as it seemed there were no options left, Mim’s fate took a dramatic turn when she was accepted into a clinical trial for breast cancer treatments.

Rob also explained how the clinical trial changed everything for his grandmother, saying: ‘There were multiple times where she had run out of options and just at that moment there was a clinical trial (that) changed the course of her cancer journey.’

Mim’s survival story became a beacon of hope for Rob and his family.

The actor said: ‘She survived and thrived longer than anyone with her type of cancer in those days.’ He added Mim’s success in the trial not only defied the odds but also paved the way for treatments that would later become standard care.

Lowe at Airbnb 2025 Summer Release on May 13 in Los Angeles

Here the actor is seen right with his longtime friend Kevin Costner 

Inspired by his grandmother’s resilience, Rob has partnered with Eli Lilly and Company to promote awareness about the importance of clinical trials into cancer treatments.

Despite the transformative role these trials played in Mim’s survival, only seven percent of cancer patients in the United States participate in them.

Rob hopes to change that, and added: ‘My great grandmother, my grandmother Mim, and my mother all had breast cancer and they helped raise me.

‘They raised me and now, in their memory, I can raise awareness about the importance of doing clinical trials.’

Rob stressed every cancer patient’s journey is different, but said the key to finding the right treatment is taking the initiative to ask about options.

He said: ‘You’re only going to know that if you actually take the initiative and ask.’