It's no secret that the marriage of Prince Charles and Princess Diana was not a happy one and a new book claims that the Prince of Wales suffered from "emotional retentiveness" so he couldn't express his feelings to his own wife. 

Royal biographer Ingrid Seward's book, Prince Philip Revealed, details her conversations with Princess Diana. The Princess of Wales, apparently, said that Prince Charles was brought up without feeling the love of his parents, Queen Elizabeth and Prince Philip, so his feelings were "suffocated at birth." 

The author writes that Prince Charles mostly interacted with his nannies who showered him with affection. However, Princess Diana thinks that this is different from the kisses and cuddles children should get from their mom or dad, and Prince Charles didn't have this experience.

The book details that, whenever Prince Charles saw his mother and father, they would shake hands and not embrace. This made Princess Diana remark that the only thing her husband learned about love from the Queen and the Duke of Edinburgh was a handshake. 

Seward also tackles the frequent separation between Prince Charles and his parents as he was growing up. Apparently, Queen Elizabeth and Prince Philip saw very little of their son and daughter, Princess Anne, that the royal couple also missed most of their children's birthday parties. 

The biographer charts the complicated relationship between Prince Philip and his oldest son. The Duke of Edinburgh was harsh towards the Prince of Wales as he was growing up that friends think he was scared of his father. 

Netflix's drama series The Crown depicted some parts of this complicated relationship between father and son, including the times Prince Charles hated his life in boarding school. Prince Philip sent Prince Charles for education far from home so he could learn to be a man. The Duke of Edinburgh felt that his oldest, the heir to the throne, was too sensitive so he needed to toughen up. 

Penny Junor, another royal expert, said that sensitivity is the least of qualities one could associate with Prince Philip so he could not relate to his son. The Duke of Edinburgh's manner of parenting Prince Charles was to criticize him, which undermined his self-esteem.  

In 2004, Prince Philip actually acknowledged why he and his son don't always see eye-to-eye. The Duke of Edinburgh admitted that he's unfeeling and sees things differently because he is pragmatic while his son is a romantic. 

Prince Philip Revealed will be out in stores on Oct. 1.