Ant and Dec wanted to keep their 'DNA Journey' show "honest".
The presenting duo - made up of Ant McPartlin and Declan Donnelly - aired their 'Ant and Dec's DNA Journey' series last year, and have said the process of discovering their family histories was "enjoyable" but "emotional".
Speaking to reporters after the National Television Awards (NTAs) on Tuesday (28.01.20), Ant said: "[The two-part series] was two and a half years in the making, [and we] ended up going to places physically and emotionally [we never thought we would].
"It was one hell of a show. We learned a lot about each other ... about ourselves. It was a really enjoyable, but emotional process."
During the filming process, production was temporarily halted when Ant was arrested for drink-driving in March 2018, and the pair considered axing the project.
But they ultimately decided to continue filming, because they wanted the series to be as "honest" as possible.
Dec explained: "We took the journey and then our lives both took a turn in the middle of filming and we didn't expect that to happen. Then that became a huge learning process for us."
And Ant continued: "We decided that we would keep it in, and talk about it, because we had to. It's such an honest show - if we'd have dodged it, it would have been dishonest. It's all in there, and the end result was crazy."
In the documentary, Ant and Dec open up about Ant's sobriety battle, with 44-year-old Dec admitting he thought he'd "lost" his best friend when he was at his lowest,
Ant, 43, said: "Y'know the last few years have been quite emotional, hard, they have been testing I would say in terms of how strong your love is and how strong your friendship is."
Whilst Dec added: "It has been a tough couple of years and it has tested the bond we have shared since we were 13 years old. I was incredibly angry at the start, so angry. Disappointed that he didn't ever come to me and say 'I am struggling, I need you' because that is what I would do if the shoe was on the other foot. And he never came to me and that hurt me a lot."
Dec was then asked if he thought he might lose Ant, and the TV star admitted he was "filled with fear" at the thought of no longer having his pal by his side.
He said: "Yes. There was a point where I thought that that was it. There were times where I wasn't sure it was going to survive. Times where you didn't know it needed to survive or you wanted it to survive.
"All the while he was away I wasn't sure where his head was at or if he was going to say 'none of this is for me'.
"I didn't know what he wanted to do and for the first time in 30 years I had to think about what I was going to do and if I was going to go out on my own. The thought of that filled me with fear."
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