Kate Middleton, the mother of Prince George, Princess Charlotte and Prince Louis, reportedly knows how to handle Prince William's temper tantrums.

Though Prince William is next in line for the throne, Kate Middleton's husband still has some growing up to do. In a new interview, author Tom Quinn discussed his new book Yes, Ma’am: The Secret Life of Royal Servants and revealed there's a portion of the tome that mentions how the dad-of-three can sometimes be immature behind palace doors.

In his new book, Tom Quinn claims Kate Middleton treats Prince William as her ‘fourth child’ due to his occasional tantrums