Ant and Dec are reduced to tears in their new ITV documentary DNA Journey as they meet long-lost family members.
The two-parter sees the presenting duo trace their family history on both their maternal and paternal sides with the help of historians and genealogists.
It also explores their incredible bond and friendship.
A trailer released today sees the pair speak about the importance of their latest joint venture.
It begins with Dec Donnelly, 44, saying: "It's not lost on us how lucky we are that we met each other.
"We get on so well. I'm getting emotional now. I don't know if I'm ready."
He adds: "I've never cried so much on telly in all my life."
In another scene, Ant McPartlin, 43, chokes up as he discovers his great grandfather - previously unknown to him - was a war hero.
I always thought I knew a fair bit about where I came from but it turns out I was wrong!
Speaking about the show, Ant 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."
Dec adds: "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."
The duo's research takes them to America and Ireland, where Dec is told his DNA is "in the ground they walk on".
Ant & Dec's DNA Journey airs in November on ITV.
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