It’s no secret that megastar Julia Roberts recently had a son. But who woulda thunk he’d already look like Ryan Reynolds?

“Most of the time when I say that I’m doing a movie with Julia Roberts people would say, ‘Oh, you’re a couple,’” “The Nines” star said of the laughs he gets from telling friends about his new movie, “Fireflies in the Garden,” which he stars in alongside Roberts. “It kills me. Let me have a love affair with Julia Roberts. That’d be fantastic! Sadly, no, she’s my mother.”

But how in the world can 40-year-old Julia Roberts play mother to 30-year-old Reynolds?

“The movie actually takes place over a great deal of time,” Reynolds clarified. “She’s a woman in her mid-30s throughout [most of] the film, while in some portions she’s much older. She’s doing a lot of prosthetic age makeup.”

All laughing aside, “Fireflies” is actually a “complicated family tragedy,” Reynolds said, an autobiographical tale centering on writer/director Dennis Lee’s own personal tragedy.

“I play this character who goes home to visit his family,” he explained of the flick’s setup. “On his way back home, for the first time in forever, his mother is killed. This family is essentially marooned together dealing with this grief.”

“Most families have a complex dynamic,” he added. “[But] there’s a great deal of tension within this family.”

With a cast like this, you’d expect nothing less. The film co-stars Hayden Panettiere, Ioan Gruffudd, Willem Dafoe, Emily Watson and Carrie-Anne Moss.