Many believed that Queen Elizabeth's favorite grandchildren are Prince William and Prince Harry, but a royal biographer claims that they aren't really Her Majesty's favorite.

A lot of people usually see the monarch with Prince Charles' son so many believed they were the favorite grandchildren. But as per Ingrid Seward, the Queen becomes more herself whenever she's with Princess Anne's children - Zara and Peter Philips.

The royal biographer said that Queen Elizabeth is closest to the two, particularly because they were her first grandchildren, that's why they have always been the monarch's favorite. Seward added that Her Majesty feels most relaxed when she spends her time with them.

During their childhood days, the Queen reportedly used to give Zara a smack around her legs, especially when she's naughty - which happens frequently. Furthermore, Seward claims Her Majesty prefers Zara and Mike Tindall over Prince William and Kate Middleton.

The royal biographer explained that even though the Queen gets along really well with the Duke and Duchess of Cambridge, she does not reportedly have the same "easy-going giggly time" whenever she's with the Tindalls. Moreover, the monarch reportedly likes the company of ordinary people such as Mike, since he is down-to-earth, can make Her Majesty laugh easily, and makes Zara very happy.

Also, Queen Elizabeth and Zara reportedly share the same passion for horses, while Middleton is allergic to horses. Back in 2009, the Duchess watched her then-boyfriend Prince William at the society polo match, but she reportedly stayed at the tent in the corner of the field.

During those times, Australian author Kathy Lette reportedly approached Middleton and asked her why she did not go to the champagne reception. However, the Duchess of Cambridge responded that she's allergic to horses.

Going back to Zara and Mike, Queen Elizabeth finds light relief with them because they keep themselves from the dramas. Her Majesty reportedly becomes more of herself when she's with the Tindalls, and she reportedly forgets the alleged feud between the Cambridges and Sussexes.

In another related report, Christopher Andersen claims that Her Majesty's favorite grandchild is Prince William. The royal biographer said the monarch has long embraced Middleton as the "suitable mate" of his favorite grandson.

However, E! News royal correspondent Melanie Bromley claims Prince Harry is the Queen's favorite since both of them were really close. She also said that the monarch's relationship with the Duke of Cambridge is "half family and half business" since he will become the future King.