Kate Middleton set strict 'life rules' with royals while expanding family with Prince William: author

Kate Middleton has made a point to put her family first.

While the Princess of Wales was expanding her family with Prince William, she established a few strict rules with Queen Elizabeth II, according to royal author and journalist Robert Jobson.

"Catherine knows her own mind and even established some fundamental life rules that she would stick to when she joined the Firm," Jobson wrote in his new book, "Catherine, the Princess of Wales," obtained by Fox News Digital.

KATE MIDDLETON...