Matthew McConaughey still refuses to test whether Woody Harrelson is his brother, despite a family story, a suspicious timeline and Harrelson’s enthusiastic willingness to provide practically any biological sample required. For McConaughey, the possible answer carries more weight than the mystery.

The actors revisited the long-running question while promoting their Apple TV+ comedy Brothers, in which they play fictionalised versions of themselves. Appearing on the Conan O’Brien Needs a Friend podcast, Harrelson made clear that he is ready to settle the matter.

“He’s fully convinced. He doesn’t want to do the DNA,” Conan O’Brien said.

“I’ll swab right now. I’ll pee in a cup now,” Harrelson replied, bringing admirable urgency and slightly unnecessary flexibility to the process.

How did the brother theory begin?

McConaughey first shared the story publicly in 2023 on Kelly Ripa’s podcast. He said his mother had hinted that she may have known Harrelson’s father far more closely than anyone previously realised.

The comment came during a holiday in Greece, when she told Harrelson: “Woody, I knew your dad...”

According to McConaughey, everyone present noticed the pause and the particular emphasis she placed on knew. It was apparently not delivered like a casual memory of meeting someone at a supermarket.

The dates made the suggestion harder to dismiss. Harrelson’s father was reportedly on furlough around the same period that McConaughey’s parents were going through their second divorce. McConaughey also said there were “possible receipts and places out in West Texas” that could place his mother and Harrelson’s father together.

He later told O’Brien that even his son, who was five at the time, understood what his grandmother appeared to be implying. The remark has since become part of the family’s shared history, albeit one that could still benefit from laboratory confirmation.

Why does McConaughey avoid the DNA test?

Harrelson views testing as a straightforward way to answer the question. McConaughey sees the potential result as something that could force him to reassess his entire childhood and his relationship with the man who raised him.

“If it turns out to be true, oh man, I got to unpack a whole 56 years,” he said.

A negative result would create a different problem, although he presented that one with rather less gravity: “And if it’s not true, he’s not going to be near as fun to hang out with.”

Harrelson offered a more optimistic interpretation. If the result showed that they shared a father, he suggested McConaughey could simply view his upbringing as time spent with a kind man before discovering another branch of his family.

“Think of it like there was a nice man in my house for all those years. It was a very sweet person. And now I got a new dad,” Harrelson said. “And you’re getting a couple of brothers.”

It is a generous framing, though perhaps easier to offer when someone else would be doing most of the emotional unpacking.

Their on-screen history already looks unusually fitting

McConaughey and Harrelson have worked together for almost three decades. They met while making the 1999 film EDtv, in which Harrelson played McConaughey’s brother. At the time, this was simply casting rather than possible advance notice from the universe.

They reunited for Surfer, Dude in 2008 and starred together in the first season of HBO’s True Detective in 2014. Their friendship continued away from the cameras, with McConaughey regularly describing Harrelson as his brother.

In one birthday tribute posted on Instagram, McConaughey wrote: “From another mother? Happy birthday brother.” That question now looks rather more literal than most social media captions manage.

The pair were also seen together in Manhattan’s Tribeca neighbourhood earlier in September 2026 and attended day 13 of the 2026 US Open at the USTA Billie Jean King National Tennis Center.

Their latest project, Brothers, pushes the relationship back on screen, this time through fictional versions of themselves. The title is not exactly helping public interest move on.

McConaughey said he will “probably do a DNA test” eventually. Until then, Harrelson remains ready, the evidence remains circumstantial and one of Hollywood’s strangest family questions stays conveniently unanswered.