Ant and Dec will discover that one of them is descended from royalty when they trace their family history for a new series on ITV.
Ant and Dec's DNA Journey will see the Saturday Night Takeaway duo joined by genealogists and historians as they follow their maternal and paternal bloodlines into the past.
The TV 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 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.
Their research will also unearth evidence that one of their ancestors' bones were deemed "of historical importance".
Similarly, EastEnders star Danny Dyer discovered in 2016 that he is related to Thomas Cromwell, Edward III, William the Conqueror and Henry III during filming for the BBC's Who Do You Think You Are?
McPartlin is preparing to return to work on I'm A Celebrity... Get Me Out Of Here! after taking a break from the show following his arrest for drink-driving in March 2018.
The TV presenter, who was replaced by Holly Willoughby on the series last year, recently reunited with Donnelly in the Australian jungle.
Donnelly hosted the live episodes of Britain's Got Talent solo last year during his co-host's hiatus, but McPartlin made his full return to the variety programme earlier this year.
Ant and Dec's DNA Journey, a two-part co-production between Voltage TV and Mitre Television, is coming soon to ITV.