"It seems, in fact, that you are immune to shame. In addition to betraying your family and causing irreparable damage to the relationships within it, you decided to betray your country by helping incite the Jan. 6 domestic terrorist attack on the Capitol," the op-ed said.
The siblings named actions Gosar took that they thought incited the riot, including sharing false claims about the results of the 2020 election.
They also accused him of gaslighting everyone by painting Ashli Babbitt, the Trump supporter who was killed by police while participating in the riot, as an "innocent bystander."
Gosar has frequently praised Babbitt. He said she was "executed" and accused the Capitol Police of "lying in wait" for her, comments that were condemned by his colleagues.
"Maybe you don't know how you got to this very dark place, Paul. Unfortunately, we have some ideas," his siblings wrote. "Maybe it's because you're in way over your head in Congress and don't have the intellect, character or maturity to be in that leadership role. Maybe your lifelong, insecure need for the approval of others caused you to sacrifice your common decency and integrity to satisfy Trump and his followers in order to keep your seat."