BEIJING — Of all the Lopez family’s achievements in these Olympic Games, perhaps the most significant is this:

Ondina Lopez boarded a plane.

You see, Ondina is the mother of Steven, Mark and Diana Lopez, the first set of three U.S. siblings to qualify for the Olympics in the same sport since 1906. And Ondina is intensely afraid of flying. The only close second is watching her children compete in taekwondo, which is what she’s here in Beijing to do.

But she’s making good on a promise made when Steven, her second-oldest son, started turning his hard work into back-to-back Olympic gold medals at Sydney in 2000 and Athens in 2004.

“She made a deal with us that if three of her kids made the Olympics at the same time that she’d finally come,” said Steven.

Ondina’s first child is Jean, who just happens to be coach of the four-person U.S. team (only teammate Charlotte Craig is not from the Lopez family tree). Jean’s not too busy and focused to step back and place the unique feat in perspective. Not since Edward, Richard and William Tritschler competed in gymnastics in 1904 has the U.S. seen such sibling revelry.

“It’s something we always dreamed of,” Jean said. “In 2005, it gave us a sneak peek that we could do this when we all won world championships. Everything just came together perfectly. They’re all at the right ages, healthy and have the experience they need to be Olympic athletes. It’s so satisfying.”

The dream for the Lopez kids (Jean, 34; Steven, 29; Mark, 26; and Diana, 24) began in the unlikeliest of places—the family’s garage in Sugar Land, Texas. That’s where they first trained and toiled amongst themselves before branching out to more structured classes.

Patriarch Julio Lopez emigrated to New York from Nicaragua in 1972, seeking a better life for himself and his wife. Unable to speak English, the structural engineer initially landed a factory job that manufactured New York Yankees hats and jerseys.

The Lopezes eventually moved to Houston, where Julio’s fascination with martial arts motivated him to enroll then 8-year-old Jean in taekwondo classes. The hobby soon became an obsession, a bond shared between parents and siblings, who are as concerned as much about each other’s fortunes as their own.

Minutes after Diana lost her quarterfinal match in 57 kilograms to a Turkish fighter who ended up winning the silver, Mark took time to console his sister—and fellow rookie Olympian—before winning his quarterfinal match.

“I just gave her a kiss and then did what she would want me to do, do my best and get redemption for her,” Mark said. “If it was the other way around, I’d put all my energy into supporting Diana, just like she did for me.”

Mark wound up winning the silver medal in 68 kilograms on Thursday after losing to South Korea’s Taejin Son in the final. Diana took bronze after she won two matches through the repechage (the Olympic equivalent of a second chance in a double-elimination tournament). Steven competes Friday in 80 kilograms.

“I wanted this more to give to (my parents) than myself,” Diana said.

Even though he’s not competing, Jean, a former world champion silver medalist, might have the toughest task of all. He’s sibling, coach and psychologist, all in one.

“They’ve got it easy because they just go out there and have fun and compete,” Jean said. “They focus on themselves and I’m the one who focuses on all three. It’s been very draining. But I knew that’s what I would be up against.”

What Ondina is up against is a return flight home. That’s no small task for a mother who made Julio eat a $1,500 plane ticket to the 2000 Sydney Olympics after he couldn’t convince her to overcome her fears.

Not that Ondina is soft. All four children claim she queries Jean often about his training schedule and reminds them not to give in to opponents. This is, after all, a woman who once killed a snake to overcome her fear of them, according to Steven.

Ondina also has influenced her children in myriad ways, not the least of which is passing on her difficulty of watching competitions because of nerves.

“When I’m competing, I’m at peace, but I can’t watch when my siblings compete,” Steven said. “I don’t cheer or anything. I just bury my head.”

By tonight, Steven’s competition will have concluded, perhaps with another gold for Steven, a full complement with Mark’s silver and Diana’s bronze. The Lopez family will begin to look toward London in 2012. For Ondina, that’s a shorter flight from Texas, anyway.

“The most anticlimactic part of this is that I can’t express the feeling,” Mark said. “You’re feeling the feeling. You know the feeling. But you can’t describe it.

“Perhaps one good way is seeing our family after Steven won his gold medals or after me, Steven and Diana won our world championships and the pure joy on our parents’ faces. My Dad let out a ‘whoo!’ That’s not a word. But maybe that describes the feeling.”