Princess Charlotte's confident personality is much like her mom Kate Middleton's, and Princess Kate is carefully shaping her daughter's path as she turns 10.

"The late Queen [Elizabeth] was always very conscious of that extraordinary and challenging role of the No. 2," royal biographer Robert Hardman, author of The Making of a King, tells PEOPLE in this week's exclusive cover story.

Royal biographer Robert Hardman weighed in on how the Prince and Princess of Wales are handling Princess Charlotte’s reality of being third in line to the throne.