It is widely believed that Prince William's failure to support Prince Harry and Meghan Markle's relationship sparked a rift between the brothers, but according to royal historian Robert Lacey, their relationship was complicated from childhood. Prince William was envious of his brother's public reputation and suffered from the pressures of being heir to the throne, the author of "Battle of Brothers" told "Entertainment Tonight" (opens in new tab).

"We spoke to Ken Wolfe, who was Harry and William's childhood bodyguard. And he said that William was always jealous of Harry's reputation as a lovable scoundrel and the love that Harry generated. And there is certainly the notion that William and (his wife) Kate were frustrated that Harry and Meghan, the royal rock stars, overshadowed them, and are now very happy that they have both left the country."

"There is the idea that it is very convenient for William to be the scapegoat for Harry and Meghan living abroad," Lacey continued.

Reflecting on the siblings' childhood, Lacey said William felt "very protective" toward Harry. 'He had the same urge when his mother got bad. It was his mother's shoulder on which he cried. I think his sense of responsibility for Harry took away the laid-back nature of his childhood. That is why, it is said, until last year he never told his son, Prince George, that he would one day be king. William felt that it was a burden to him as a child and that he did not want his son to become one."

Asked if William and Harry would ever be reunited in a royal capacity, Lacey doubted it. 'I think we have to face the reality that they are brothers who learned two different lessons from a troubled childhood and they are going in different directions. 'I think the best we can hope for is that they can maintain their basic love and respect for each other and have a good relationship going into the future.'