Invariably people want to know how much of Nia Vardalos' hit film "My Big Fat Greek Wedding" is true.

Almost all of it.

"It's not a documentary but, yeah, it is my true story," Vardalos said on a recent publicity visit to Kansas City with co-star John Corbett. "I was a geeky Greek-American girl who did marry a guy who actually was baptized in the Greek Orthodox Church so we could have the ceremony. My husband is named Ian, and he is a vegetarian. I do have 27 first cousins. My father really thinks he can find the Greek origin of every word in every language."

Of course, in real life Vardalos grew out of her geekiness much earlier than does Toula, her late-blooming movie alter ego. She spent eight years performing on the stages of the Second City comedy companies in Toronto and Chicago (where she met her husband, comic actor Ian Gomez of "The Drew Carey Show" and "Felicity") before coming to Los Angeles and launching an acting career.

Growing up in Winnipeg, Manitoba, Vardalos found herself torn between the traditions of her large family and her desire for freedom and self-expression. Finally those two seemingly contradictory influences came together in a one-woman play, "My Big Fat Greek Wedding."

"I wouldn't exactly call it a love/hate relationship with my family...but I always knew we possibly were the loudest people on the planet," she said. "I wanted to present their behavior in a loving way. Doing the play, and now the movie, has helped me make peace with my very large ethnicity."

But there's no getting away from kin, Vardalos conceded. "They love me so much that 49 of them just showed up for the film's premiere in L.A. They paid their own way, trading frequent flier miles to get there."

The film was produced by Tom Hanks and his actress wife, Rita Wilson. Wilson caught a performance of Vardalos' stage show and suggested to Hanks that it should become a movie.

"I'd talked to other film producers," Vardalos recalled, "but they were saying things like, `Well, we need to change it to an Italian family'...and they wanted Jennifer Lopez to play me.

"But when I told Tom `I'll play the lead,' and he said, `Yes, of course,' I knew I'd found the right people."

Corbett, currently a major heartthrob thanks to his recurring role on HBO's "Sex and the City," came to the project at the last minute. Both he and Vardalos think fate was trying to tell them something.

"My agent had sent me this script and I loved it," Corbett recalled. "It was as much fun to read as it is to watch the finished movie. But then he called back and said he shouldn't have sent it to me because they'd already offered the part to someone else. That really ruined my day.

"On the last day of shooting last season's `Sex and the City,' I'm in my hotel room, and I get a call from some friends. They're downstairs, and they want to meet me in the bar. So I go down and I'm talking to them and they ask if I'd read anything good lately. And I said there was this script about a Greek wedding that I was dying to do but the part was already cast."

What Corbett didn't realize is that sitting nearby was Vardalos, along with "Wedding" co-producer Gary Goetzman. They overheard Corbett's comment.

"This was amazing, to hear John say he liked my script so much," Vardalos said. "And the weird thing is, we had just let go of the actor we'd cast for that role because there was never really any chemistry between him and me. We were only four days away from shooting, and we didn't have a leading man. And here's John talking about how much he liked our script!"

Vardalos said she knew right away that this was the guy who would be her co-star. "I liked him instantly. For a lot of reasons, but initially because, well, he's cute."

That may be an understatement. His performance as Sarah Jessica Parker's love interest on "Sex and the City" has turned the bachelor Corbett into a poster boy for the sensitive, sexy male. Ironically, it all plays a bit like the old episode of "Northern Exposure" in which Corbett's character, Chris the radio deejay, begins secreting pheromones that make him irresistible to women.

Asked about his newfound hunk status, the quiet, understated Corbett shrugged and gave an embarrassed smile. "It's a phenomenon," he said. "It's just women, women, women..."

Vardalos, who has witnessed this phenomenon first hand, shook her head in disbelief: "Earlier today we came out of the radio station broadcast booth where we were being interviewed, and there were like 15 women standing there -- intelligent women, career women -- and they've all got Instamatic cameras with the price tags still hanging on them. They're slipping their wedding rings into their pockets."

"Greek Wedding" opens in Kansas City theaters today, but it has been playing in several major markets for the last month -- and has been racking up huge numbers.

"Last week we were playing in only 250 theaters, and yet we were one of the Top 10 films," Corbett noted. "How can this be?"

The answer is simple: Audiences love the film and tell their friends to see it.

"Early on they did a test screening of the movie -- with non-Greek people," Vardalos recalled. "It tested so high that the film immediately became the talk of the town."

"In fact," Corbett added, "it tested better than `Sleepless in Seattle' did."

Vardalos said she's been stunned by the film's reception. And, typical of her upbringing, she's been trying not to get too excited by it.

"All the time I was working on the film, I didn't tell anybody about the project. I didn't make any big purchases. I didn't want to jinx it. It's the Greek tragedy part of me."