Woody Harrelson and Matthew McConaughey may want to call in a true detective for this one. 

After McConaughey suggested he and Harrelson could be half brothers, the Cheers alum weighed in on the possibility.

"Well, I'll just say there is some veracity to that thought," Harrelson, 61, said on the April 18 episode of The Late Show With Stephen Colbert, "because we talked to Ma Mac, Matthew's legitimate mother, and she let us know one time—it's crazy, we were in Greece. We were watching the U.S. team win the World Cup, and I don't know, I mentioned something about regrets. And I said, ‘You know, it's odd that my father has no regrets.' And I've known Ma Mac a long time, and she goes, 'I knew your father.'"

As he explained, it was how McConaughey's mother Mary McCabe said it that caught his attention.

"It was the ellipses I found a little troubling or interesting. 'I knew your father,'" Harrelson said, going on to describe the pause as "filled with innuendo."

The Triangle of Sadness star also indicated the timing would make sense.

"The year of his [McConaughey's] birth, nine months before," he said, "she was on a sabbatical from her relationship with his supposed father Jim."

And Harrelson noted the actors want to further explore whether they're related.

"The thing is we want to go and test," he shared. "But for him, it's a much more big deal. I mean, he feels like he's losing a father. But I'm like, no you're gaining a different father and a brother."

McConaughey—who appeared alongside Harrelson in the show True Detective—first brought up the potential family ties last week.

"In Greece a few years ago, we're sitting around talking about how close we are and our families and etcetera and my mom is there. And she says, ‘Woody, I knew your dad,'" the Oscar winner, 53, said on the April 12 episode of Kelly Ripa's podcast Let's Talk Off Camera. "Everyone was aware of the ellipses that my mom left after 'knew.' It was a loaded K-N-E-W."

And he also noted the timeline would add up.     

"We went on to unpack this what 'knew' meant and did some math and found out that his dad was on furlough at the same time that my mom and dad were in their second divorce," McConaughey added. "Then there's possible receipts and places out in West Texas where there might have been a gathering, or a meeting or a 'knew' moment."

If the duo were to be half brothers, they wouldn't be the only stars with famous family members. To see more celebrities you may not have known are related, keep scrolling.

The Mask of Zorro star was married to the Fifty Shades of Grey actress' mother Melanie Griffith for 20 years before they ultimately split in 2015, but that doesn't mean the stepfather and daughter's bond has been severed.

Johnson got emotional when she presented an award to Banderas at the 2019 Hollywood Film Awards.

"I come from a family of many a marriage and I got very lucky," Johnson, whose dad is actor Don Johnson, said. "I got a bonus dad who I realized that, over time, is actually one of the most influential people in my whole life," she said. "When I was six years old, my mother married a man who brought an unbelievably bright light and a whole new world of creativity and culture—and one remarkably magical little sister into our family."

The Teen Witch star and the Gossip Girl alum are half-sisters who share the same mom, talent manager Elaine Lively.

The "Ex's & Oh's" singer is the SNL vet's daughter, born from his relationship with former model London King.

The rapper and Fast & Furious franchise star is cousins with the R&B singer thanks to her stepfather, Reverend Edward Best, who happens to be Luda's uncle.

The late-night host and the Rescue Me creator are third cousins.

The onetime Grey's Anatomy doc has called the legendary director stepdad ever since he married her mom Kate Capshaw in 1991.

The Grown-ish star calls the rapper her second cousin. She was even the flower girl in his 2005 wedding with now ex-wife Kelis!

The star of The Politician is also the daughter of the Back to the Future icon.

Not only did the Veep vet make a name for herself playing a famous daughter on the HBO comedy, but she's also a famous daughter in real life. The erstwhile Jack Bauer star is her father.

Some Emily in Paris viewers were très shocked to discover Lily is the daughter of the English Grammy winner. 

The comedian and the New York Senator are actually related, as he's the first cousin of her father.

According to a 2014 People interview, a family historian from Ancestry.com claimed that the Fannings and the Duchess of Cambridge are all descendants of King Edward III, who ruled England from 1327 to 1377, making them very distant relatives—21st cousins, to be exact.

The actors are actually brother and sister!

The SNL alum calls the Cheers icon Uncle George whenever he seems him. At least, we assume he does.

Yep, Game of Thrones' Stannis Baratheon is the real-life dad of Fear the Walking Dead's Nick Clark.

The brunette beauty and the soulful "Stay With Me" crooner are third cousins. During a radio interview, Smith admitted that the pair have never met because their family is "huge."

The Salt actor and the memorable Law & Order: SVU guest star are half-brothers.

You may not have guessed but the Bridesmaids comedian and The View co-host are cousins.

The gorgeous British model is the eldest child of the Bush lead singer. The father and daugher first met when Lowe was 14 after she requested a paternity test. 

The We're the Millers actress has the perfect mentor in the Pretty Woman star, who happens to be her auntie.

Who knew the stunning Dancing With the Stars pro is second cousins with the Friends star?

The sexy True Blood vampire caught the acting bug from his dear old dad who stars in both The Avengers and Thor franchises.

The Ghost Rider actor comes from an extremely talented family. One of his cousins directed The Bling Ring, the other starred in Saving Mr. Banks and his uncle directed The Godfather.

The outspoken British singer is the older sister of the Game of Thrones star. She even wrote a song about him titled "Alfie."

 

The Damages star and the Lipstick Jungle actress are second cousins.

The Secret Life of Walter Mitty actress originally inspired her baby brother to get into show business.

The gorgeous Parks and Recreation actress is the daughter of the legendary music producer.

The Lost actor has a very famous cousin in the Mission: Impossible action star.

The "Drop It Like It's Hot" rapper is first cousins with The Game actress and her brother, Ray J.

The Anger Management star is the youngest brother of The Breakfast Club actor.