Are Woody Harrelson and Matthew McConaughey really brothers?

No one seems to know, but Harrelson wants to find out.

On Tuesday’s episode of “The Late Show with Stephen Colbert,” Harrelson explained what has become Hollywood’s latest buzz-worthy story.

“We want to go and (do a DNA) test, but for him, it’s a much more big deal,” Harrelson said. “I mean he feels like he is losing a father. But I’m like, no, you’re gaining a different father and a brother.”

Last week, when appearing on SiriusXM podcast “Let’s Talk off Camera with Kelly Ripa,” McConaughey, 53, revealed that he and Harrelson, 61, could be half-brothers as his mother had told them both that she “knew” Harrelson’s father during a time when she was separated from her husband.

The Oscar winner, who was teasing the pair’s new series “Brother from Another Mother,” also noted how their families often confuse them in photos.

“Well, I’ll just say there is some veracity to that thought because we talked to Ma’ Mac, Matthew’s legitimate mother, and she let us know one time … I mean, this is crazy. We were in Greece, we were watching the US team win the World Cup and I don’t know, I mentioned something about regrets,” Harrelson told Colbert.

“And I said, ‘You know, it’s odd that my father has no regrets.’ And I have known Ma’ Mac a long time, and she goes, ‘I knew … your father.’ And it was the ellipses I found a little troubling, or interesting. ‘I knew your father.’”

McConaughey and Harrelson first worked together on the 1999 film “EDtv” and have since reunited for the 2008 comedy film “Surfer, Dude” and in season one of HBO’s “True Detective.”

Mark Heim is a reporter for The Alabama Media Group. Follow him on Twitter @Mark_Heim.