Prince William and Kate Middleton (opens in new tab) are committed to treating all three children as equals, but there is something about their oldest son, Prince George (opens in new tab), that sets him apart not only from his siblings, but from, well, almost everyone on the planet. In fact, only a few of George's relatives really understand that. George is the direct heir to the British throne, something that only his father Prince William (opens in new tab) and grandfather Prince Charles (opens in new tab) share.

According to royal historian Robert Lacey, Will and Kate gave George a lot of thought about how and when to explain to him that he would one day be king and what that would mean.

In a new chapter of his book Battle of Brothers (opens in new tab), Lacey explained that the Cambridges are believed to have told George the news around George's seventh birthday in July 2020.

"William has not revealed to the public how or when he told his son the big news. Maybe one day George will tell us himself. But it is believed that around the boy's seventh birthday in the summer of 2020, his parents explained in more detail what the little prince's future life of "service and duty" in the royal family would be like in particular," Lacey writes in a new chapter, the Daily Mail (opens in a new tab) It reports. The prince stressed that his goal as a father was to give his son a "normal upbringing in a normal home" so that the monarchy would be "fit for the modern age and not lag behind."

As the Daily Mail points out, if the timeline of Lacey's conversation is accurate, when George posed alongside the Queen, Prince Charles, and Prince William (opens in new tab) for the instantly iconic "Four Monarchs" photo in December 2019, the royal family was unaware of his future role in the royal family.

Royal author and expert Katie Nichol (opens in new tab) has in the past suggested that Will and Kate were trying to "gradually" introduce the fact that George would one day become monarch, but that the young royals, in order to spend more time with their great-grandmother, the Queen (and of course, the portraits of the four monarchs ) often because of things like "special treatment," he stated that he had known for some time that he was "different" from his siblings.

"They feel that their three children are equal, and they value making sure everyone is treated the same," Nicole said of Will and Kate's parenting strategy OK!