Actress Alice Englert had no idea how erotic her director mother Jane Campion's movies were as a child because she was always sheltered from her mum's work.

The Australian star admits it was only when a friend broke the news to her that she learned the truth about the type of movies the Oscar-winning filmmaker made, which include erotic thriller In The Cut and classic romance The Piano.

She tells Britain's Guide magazine, "I was 13, and these boys had said, 'Your mum makes sexy films,' and I said, 'She doesn't.' Then I watched them and my mum makes sexy films."

Englert has since grown to love her mother's work, but admits she struggles to take any criticism about her work.

She adds, "I'm a huge fan of my mum. I only recently realised that if someone was to say something bad about her, I can't punch them. That that's not appropriate behaviour. I'm very protective."