The younger generation of the royal family has become exceedingly popular in recent years, with Princes William and Harry and their respective partners, Kate Middleton and Meghan Markle, often grabbing headlines and being deemed as "The Fab Four." However, a new unauthorized biography seems to indicate that the rise in popularity of his eldest son has made Prince Charles feel threatened.

According to People Magazine, the new book, "Rebel Prince: The Power, Passion and Defiance of Prince Charles," written by British investigative journalist Tom Bower, Charles, the Duke of Cornwall, felt "usurped" by Prince William and Kate Middleton and "isolated" from his grandchildren, Prince George, 4, and Princess Charlotte, 2, when the family opted to spend Christmas with her parents, and set up their home base miles from his residence.

He claims that Prince Charles, who is next in line to inherit the throne after his mother, Queen Elizabeth II, became fearful that he was going to be overshadowed by his sons as their popularity began to grow, especially after William married Kate in 2011.

"Charles saw Kate and William as the new stars and feared he'd be in trouble," Robert Higdon, the vhief executive of Charles' charity foundation in America told Bower.

In addition, Charles has always reportedly felt that both Prince William and Prince Harry have kept themselves distant from him because of the negative attention his divorce from their late mother, Princess Diana, caused them as children. That situation was reportedly not helped when Charles married his mistress, Camilla Parker-Bowles, the Duchess of Cornwall, in 2005.

The claims come after endless speculation that William and Kate would actually be able to ascend to the throne ahead of his father, with a recent report by The National Enquirer claiming that the two were going to actually be named the next king and queen in a plot to make them Queen Elizabeth's successors. Gossip Cop later refuted that story.