Knightley's outgoing persona 'an act' - mum

Keira Knightley's playwright mother sees through her daughter's public persona because she is really an introverted person.

The 20-year-old British beauty is more likely to stay home with her head in a book than out socialising according to mother Sharman MacDonald.

MacDonald says: "She's not an extrovert at all. The way she comes across in her publicity and television interviews is nothing more than a public front. We tend to spend most of our time with our heads buried in a book.

"Reading is like a drug for us. People say it's anti-life, but we can't help it. My father ready three books a day, and the kids have grown up surrounded by them."