Duchess Catherine would need to be "superhuman not to feel the pressure" of her role.
The 38-year-old royal - who has Prince George, 6; Princess Charlotte, 5; and Prince Louis, 2; with Prince William - is a strong character but faces mounting public expectation, according to royal expert Sarah Gristwood.
The author of Elizabeth: The Queen and the Crown told People magazine: "Those who know her say there is a real core of strength, and she did set her mind to the job.
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