The congressman's brother David caught the eye of Brill's campaign through his criticism of Paul Gosar on Twitter.
"I think my brother has traded a lot of the values we had at our kitchen table", Joan said. "We had to stand up for our good name". "This is not who we are", David Gosar says. "It's appalling. It's disgraceful", David Gosar said.
"Paul Gosar the congressman isn't doing anything to support rural America", says Grace, touted as simply a rural physician, as the ad opens. "They also remarked about their brother's positions on health care, immigration, and the environment".
"My siblings who chose to film ads against me are all liberal Democrats who hate President (Donald) Trump", he wrote.
Every family has their political differences. but this is on another level.
He added: "To the six angry Democrat Gosars - see you at Mom and Dad's house!"
Paul Gosar tweeted Saturday that he's "Mom's favorite", after The New York Times reported that his mother was "shocked" and "crushed" to learn of the campaign ad. "I bet he'd be researching what is the most insightful water policy to help Arizona sustain itself and be successful", says Jennifer.
Gosar took to Twitter in response to his siblings' remarks, pointing out that none of them were Arizona residents and said he wouldn't "be deterred from fighting for our conservative values".
WATCH: Arizona Rep. Gosar's 6 siblings publicly endorse his opponent in ad
All of these people are Paul Gosar's siblings.
The other siblings then identify themselves, as do Joan and Gaston, and endorse Brill.
A political campaign commercial aimed at Republican representative Paul Gosar, from the state of Arizona, has gone viral in the U.S. thanks to its twist ending, which contains some of the more pure savagery we've ever witnessed.
Following the death of counterprotester Heather Heyer during a white nationalist rally in Charlottesville, Virginia, Gosar pushed the conspiracy theory that the riots were "created by the left" and billionaire George Soros in an interview with VICE News.
Gosar first won election in 2010, his first foray into politics, with the support of the Tea Party. He also said Soros, a Democratic fundraiser, collaborated with Nazis during World War II, a claim pushed by far-right pundit Alex Jones and InfoWars.
"He is not listening to you, and he does not have your best interests at heart", "Tim" agrees - before dropping the bombshell line: "My name is Tim Gosar".
The letter went on to say that 'It is extremely upsetting to have to call you out on this, Paul, but you've forced our hand with your deceit and anti-semitic dog whistle. David Gosar. Grace Gosar.
If there is a bright side for Mr Gosar, it's that he is one of 10 siblings.