At this time last week, Lijana Wallenda-Hernandez was feeling a little stressed. There was the water, the height, the mist. There were the cameras, the reporters, the 125,000 Canadians waiting in the dark, the two years of negotiating and changing laws, all leading to this one day: the day her little brother would tightrope walk across Niagara Falls.

“It was awesome. It was breathtaking to watch,” says Lijana, who took in the stunt at the falls with the rest of the Flying Wallenda tightrope-walking clan. “It was also very nerve-wracking. I would rather have been the one up there than watching him do it.”

Nik and Lijana grew up tightrope walking. From the time she can remember, there was always a wire in the backyard, and the brother and sister would play on it together, imitating their wire-walking parents. Today, both are professional tightrope walkers, though Lijana—whose husband is in the tightrope act in Absinthe—is taking some time to focus on her 16-month-old son. Together, Nik and Lijana have staged their own high-wire stunts, including a Detroit walk suspended between two cranes where they met in the middle and Nik jumped over Lijana before continuing their walk.

But last Friday’s stunt was for Nik alone: a long trip across 1,800 feet of wire suspended 200 feet above Niagara Falls—the first ever tightrope walk directly above the falls and the first such stunt there in a century. Crossing over the falls poses special challenges, says Lijana—the rushing water messes with the visuals, and there’s no way to simulate the experience lower to the ground. “There are variables that he’s not used to, that no one’s used to.”

Still Lijana says she was confident in Nik’s ability to get across—even with the specter of five relatives dying in such stunts.

“I knew that he was capable. He’s a very tried and true wire-walker,” she says. ABC, which televised and sponsored the stunt, was somewhat less sure that Nik would make it across. The network forced Nik to wear a harness and tether for the attempt—a safety precaution that Lijana says is more of a hindrance than a help to an experienced walker. He even considered taking it off mid-walk if it got caught on the pendulums holding the wire taunt, according to Lijana. In the end, he made it across with tether intact, getting a passport stamp on the Canadian side.

“It’s mind over matter,” Lijana says. “There is something about being up that high … it takes a lot of guts. We’re human, too. We’re not these machines. It’s not fear, but there is a deep respect. If I mess up, I fall. That’s it.”