Dr Jonathan Spangler, of Manchester Metropolitan University, argued that the baby’s position as the offspring of a second-born royal son will offer him or her greater freedom than the Cambridges’ children.
But Baby Sussex, who is due this month, will, just like Harry did, face scrutiny over their behaviour as they grow up as part of the Windsor family.
Dr Spangler, who specialises on the institution of monarchy, said: “There are three Cambridge children and maybe there will be a fourth.
“There will be plenty of royal duties for them to do, and less and less for Harry’s child to do.
“But Harry and Meghan’s child will still be expected to live up to a certain standard.
“You can see that problem with Harry’s life as well. He was held up to a much higher scrutiny than his friends.”
The duke, born a spare to an heir and the second son of the Prince and Princess of Wales, used to be known for his scuffles, scrapes and scandals.
In his youth, William’s impulsive younger brother brawled with a paparazzi photographer, dabbled with cannabis and sparked worldwide outrage by dressing up as a Nazi for a fancy dress party.
He even confessed in 2017 that he once “wanted out” of the royal family, but said he “decided to stay in and work out a role for myself”.
Dr Spangler added: “The people Harry went to Eton with went off to parties, got drunk and nobody published their pictures in the newspaper.
“He had this double standard always – he was expected to be a teenager but not allowed to be one.
“That problem will recur again in the next generation.”
Unless the Queen intervenes, Baby Sussex will not be an HRH because George V limited titles within the royal family during the First World War.
“People who are not HRHs are free to go off and start business ventures and companies and whatever they like,” the historian said.
“Harry and Meghan’s baby could grow up to be a bit more normal, or as normal as they can be in this media-centred world.”