Actress Rachel Blanchard is puzzled about why her threesome scene in new film WHERE THE TRUTH LIES earned the movie a restrictive NC-17 rating - because even her mum wasn't offended.

The Canadian star is romanced by Kevin Bacon and Colin Firth in the period film and decided to test her intimate scenes with the two actors on her mother.

And, when censors slapped a NC-17 rating on the project, Blanchard feared plans to premiere the film for her mum were a mistake.

She explains, "My mom had heard about all the hype and her friends all went to see it. I think she was nervous about the hype but she said, 'I don't know what all the fuss was about.'"

Blanchard admits she was terrified about shooting sex scenes in the film, but was quickly put at ease by her thoughtful co-stars.

She adds, "Kevin and Colin made me feel so comfortable. There was so much going on in that scene that I was focusing on. We got to shoot the scene without stopping or starting, almost like we were in a play, so we just got lost in the scene.

"Even if someone really creepy was being really nice you could still sense that creepiness, but they were just real gentlemanly."