Charlotte Gainsbourg sent text messages to her actress mother Jane Birkin every day while filming horror/drama ANTICHRIST - so she could laugh about the traumatic scenes she had to shoot.
Gainsbourg was terrified of her role in Danish moviemaker Lars von Trier's violent and graphic film, in which her character mutilates her own genitals while struggling to cope with the loss of her only child.
So the 37 year old turned to her mum Birkin for approval - and to find humour in filming the brutal scenes.
She explains, "I had a real dialogue with my mother during the shoot. I needed to make jokes about the whole thing. It was so heavy and it was great to be able to describe my day to her and joke with her about what I was doing.
"It was like, 'Guess what I've been doing today?' You know, my day would go from crying and howling and screaming into the sex and the blood. It was hysterical and to put it into words in a text message was hilarious."
Gainsbourg even referred to her mother's sexually explicit 1969 movie Je t'aime... moi non plus, directed by her French filmmaker father Serge Gainsbourg, to feel justified in taking on such a daring part.
She adds, "It's true that for this film I did refer to my mother a lot, in the sense that she had done Je t'aime... moi non plus, and it was very shocking at the time. And she was into a lot of sex scenes and nudity and it was like permission for me to do it myself.
"It's like she had been on that journey before me and, really, it gave me the authorisation to do what I was doing and to know that it was OK, even to feel good about it and not ashamed."