Harrelson told 'Esquire' a story that might also have everyone else convinced.
During an "Explain This" segment for Esquire, Theroux straight-up asked Harrelson if he and McConaughey are actually brothers. Harrelson, who co-stars alongside Theroux in the new HBO limited true-crime series, White House Plumbers, said he's not sure "because we haven't done the testing."
The DNA testing is an idea that's been previously thrown around, but apparently hasn't come to fruition yet. But Harrelson then explained that "there's a lot of -- almost insane -- coincidences" that has him convinced they're related.
"His mom had a relationship with my dad right around the time he was conceived," Harrelson explained. "That seems like a big coincidence. And his dad did say -- you know, [when] she was going to the hospital to give birth -- he goes, 'That ain't my son.' And he didn't go to the hospital."
Theroux's mind was blown, prompting him to say, "No. Way! I didn't know that detail."
Harrelson said that's a tidbit he knew about McConaughey long before he spoke to McConaughey's mom (whom he refers to as Mom Mac) about her "shenanigans."
Back in April while on Kelly Ripa's SiriusXM podcast, Let's Talk Off Camera, McConaughey revealed he had learned his mom, Mary Kathlene, "knew" Harrelson's dad, Charles, back in the day. While recalling a trip to Greece, McConaughey said he, Harrelson and his mom were sitting around a table when she intimated having hooked up with Charles, who died in 2007.
"In Greece a few years ago, we’re sitting around talking about how close we are and our families. And my mom is there. And she says, 'Woody, I knew your dad,'" McConaughey said, with an emphasis on the word "knew." "Oh, everyone was aware of the ellipses that my mom left after knew. It was a lovely k-n-e-w. Well, we went on to unpack what this ‘knew’ meant. And [we] 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. Then, there’s possible receipts in a place that’s out in West Texas where there might have been a [inaudible] or a meeting or a ‘knew’ moment."
Ripa, like everyone else, wondered if they had signed up for one of the popular DNA tests to see if there's anything else to discover between them. McConaughey joked that a DNA test should be part of the project, Brother From Another Mother, a series about their families "based on truth."
"While Woody and I are the best of friends we have different approaches in how we raise our children and how we go about certain things," he said. "I may be a little more organized in certain things. This is a love story. It’s a story about us, he and I and our families come together. "
McConaughey's mom and dad, James Donald, got married three times. James Donald died in 1992. McConaughey revealed in his Greenlights memoir that his father died after climaxing while having sex with his mother.
"He's always told me and my brothers,'" the actor wrote in his book. "'Boys, when I go, I'm gonna be making love to your mother.' And that's what happened. He had a heart attack when he climaxed."