He also wants to be governor of Vermont. Not when he grows up, but now.
And thanks to the fact that there are no state laws that require gubernatorial candidates to be a certain age, Ethan is officially the youngest candidate to run for that office in Vermont history.
Ethan, who lives in Bristol, is campaigning ahead of the state's Democratic primary in August, where he'll face two challengers.
His issue? Stricter gun control, legislation he says his home state needs.
But being 13 poses some unique challenges for a candidate.
One of them, says Vermont Democratic Party Executive Director Conor Casey, is school.
"It's funny, his biggest barrier is complications to being in school while simultaneously running for governor -- not that I'm advocating that he drop out," Casey said.
"Also, not having a driver's license. He's dependent on other people for rides to statewide events he speaks at."
Ethan says his age shouldn't be a factor; his perspective should.
His platform has featured gun control since he announced his candidacy in 2017.
"I'll admit when I first heard about a 13-year-old running, I thought, 'Is this some kid from Willy Wonka and the Chocolate Factory, spoiled?' But that's not the case," Casey said.
"Ethan really did embrace the gun issue early on. He's representing younger people and he's been a good voice for them."
Ethan acknowledges hunting is an important part of life in New England.
"It's a culture that I respect," he said. "But if it's making the decision between letting my friends have a good time at a firing range and them possibly being involved in a school shooting, I'm choosing legislation to protect them from that school shooting."
Sonneborn says part of his campaign is intended to disrupt the status quo.
"There's always been a sense of, 'We don't talk about that in politics.' That's what I wanted to change," he said.
Ethan's parents aren't very political, he says. But his passion was stoked early on when he bought an encyclopedia featuring Robert F. Kennedy at a local garage sale when he was 5.
"I've always admired some of the great coalition builders of the modern era -- MLK Jr., Robert F. Kennedy -- who came from all walks of life to accomplish a common goal," Ethan said.
"You don't have to be a Kennedy or a famous minister to be a coalition builder. You just have to have an issue you care about and be willing to speak out on your platform."
And he does that very well, says Jessica Barewicz, his principal at Mt. Abraham Union Middle/High School.
"He has clear, concrete, research-based ideas for improving Vermont and society as whole," she said. "That is quite an accomplishment of concerted critical thinking, civic participation and a visionary nature for a middle school student."
Ethan says he's met Gov. Phil Scott, who told him his gubernatorial bid is "very cool."
Vermont Secretary of State Jim Condos told CNN that while there's no current law that prohibits Ethan