Ant McPartlin and Declan Donnelly will discover that one of them is descended from royalty when they trace their family history for a new series.
The BAFTA-winning TV presenters are taking part in a new programme called Ant and Dec's DNA Journey, on which they are joined by genealogists and historians as they follow their maternal and paternal bloodlines into the past.
The Saturday Night Take Away stars, both from Newcastle upon Tyne, will journey to Ireland as well as to the US, where they will visit the United Nations headquarters in New York.
One of the duo will discover that their great-grandfather was a celebrated war hero while the other will find out that their cousin is a former US female wrestling promoter.
Speaking about the documentary McPartlin said: "I'm a bit of a geek when it comes to historical events, so to get the chance to research our family history using our DNA was too good an opportunity to pass up. What we find out is mind-blowing and nothing either of us could ever have imagined. It's something that will stay with us both forever."
Donnelly added: "A huge part of this was to find out my heritage, especially on my dad's side. I always thought I knew a fair bit about where I came from but it turns out I was wrong! Whilst it was incredible to find out about the past, what was hugely overwhelming was to meet relatives neither of us knew we had. It was a truly amazing experience."
Ant and Dec met while working as actors on a BBC children's programme called Byker Grove in 1989, they then tried their hand at music for a while (Let's Get Ready to Rumble, anyone?!), but stardom struck when the duo became presenters on the children's programme Gimme 5 in 1994.