Everyone has an if/then moment that leaves them wondering what might have happened if life went another way, and the opening night performance of parallel-lives Broadway musical “If/Then” gave opening nighters reason to recall theirs.

Take composer Tom Kitt, who reteams with collaborator Brian Yorkey on “If/Then” after the duo won a Pulitzer for musical “Next to Normal.” If the Columbia U. soccer coach hasn’t recruited Kitt for Columbia, then Kitt never would have met his wife, who never would have introduced him to Yorkey.

If Kitt’s if/then moment had turned out differently, then he might have worked for Morgan Stanley, which offered him a job that he turned down to pursue songwriting. If Yorkey’s if/then moment had gone another way, he’d be dead.

Yorkey was 11 when his sister took the car out to pick up his other sister. “She asked if I wanted to come and get Big Gulps, which is what we did back then, but I was in the middle of a Hardy Boys book so I said no, I’m gonna stay home and read,” Yorkey recalled at the “If/Then” opening night party at the Edison Ballroom. “That day my sister was broadsided and the whole car was totaled except for the drivers seat. She got out with just a few scratches, but if I’d been in that car I wouldn’t be alive today. We all have those moments, right? You look back on it and you think, ‘The Hardy Boys saved my life!’ ”

For Idina Menzel, the “Frozen” and “Wicked” star making her return to Broadway after a decade, her if/then moment hinges on a part she didn’t get in a show directed by Michael Greif, who helmed both “If/Then” and “Rent,” the tuner that launched Menzel’s career. “If I hadn’t auditioned for Michael in a show no one’s ever heard of, he wouldn’t have seen me and then brought me in for ‘Rent,’ ” she said. “But the whole point of ‘If/Then’ is not to look back so much, and to understand that the choices you make set a pathway but they don’t define you.”

At the moment, she’s thrilled that the path she’s chosen has brought her back to Broadway. “I feel closest to myself when I’m here in New York working with this community,” she said. “It’s hard to explain. It reinvigorates me. It just feels closest to who I am.”