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Director Jason Reitman knew life changed when his first movie Thank You for Smoking was a hit.

Not because of reviews or box office success but because his father, director Ivan Reitman, began asking for advice.

The younger Reitman, 30 is now nominated for a best director Oscar for his breakthrough low-budget comedy, Juno, one of four Academy Award nods the film has received including best picture, best actress for its star Ellen Page and best original screenplay.

Despite his success, Reitman says he was concerned his latest offering would fail to live up to the first. But offsetting that worry was the fact he had already impressed his dad, whose work ranges from directing the 1984 hit Ghost Busters to producing the 2003 comedy Old School.

After Thank You for Smoking, his father began regularly seeking his advice about movie-making.

"I've spent 30 years asking him for advice on any big decision I've ever had. The fact he would now come to me for advice is," Reitman reflected, "wonderful beyond words."

Reitman seems down to earth for a young filmmaker. He answers questions thoughtfully and tells stories with self-deprecating humour. He is not a fixture at Hollywood nightclubs but a family guy - married with one child.

In fact, he was sought out to direct Juno at roughly the same time his wife became pregnant, and the timing seemed perfect.

Juno is an unconventional teen romance dealing with marital and family relationships. It stars new talent Page as a 16-year-old who becomes pregnant, decides to have the baby, then opts for prearranged adoption.

Juno is a far cry from Thank You for Smoking, a political satire dealing with a tobacco industry lobbyist. It premiered at the 2005 Sundance Film Festival, won strong reviews for its humour and insight, and grossed US$40 million ($51 million) at global box offices - not bad for a US$6 million movie.

Reitman said well before he began work on Juno, he was writing a screenplay similar to Smoking and was concerned he might become known for doing just one type of film.

"Being the son of a filmmaker, you are aware of a career as a director. You don't think of it as just movies, but as a life," he said.

"I couldn't help but wonder how my life was going to go ... One film does not make a career."

Because Juno involves the politicised issue of teen pregnancy, it could have been dragged into the national debate over abortion. But Reitman reckons the film's sense of humour has helped prevent that from happening.

Whereas the comedy in Smoking stemmed from its political satire, in Juno the humour is derived from human frailties and family dynamics.

"If we had made it as a straight drama, people would emotionally take sides and not listen. But because of the humour people start enjoying the film for its story," he said.

Reitman credits his wry sense of humour to the perspective he developed growing up as "kind of a loser in high school," as well as to a "very funny mother and father."

"Thank You for Smoking was my proving ground. (My dad) really recognised me as a filmmaker in my own right," Reitman said. "I always had a great storyteller on speed dial, and he realised he had [one] on speed dial, too."