One the French actress of The Da Vinci Code movie, Anthony Lane wrote:
"as for Audrey Tautou, it is surely no coincidence that Howard sought out and hired almost the only young French actress who emits not a hint of sexual radiation."
I don't think Lane got it. The point of Audrey Tautou is not her sexual appeal - but the fact she looks like a potential psycho-stalker. Hence she should have been offered the Silas role instead.
Full New Yorker review of The Da Vinci Code.