Prince Philip never did this one particular thing that Prince Charles, Prince William and Prince Harry do.

According to royal expert Marlene Koenig, the Duke of Edinburgh was a very different father compared to the Prince of Wales, Duke of Cambridge and Duke of Sussex. While Prince Charles, Prince William and Prince Harry were doting dads, the 98-year-old senior royal lacked "affection" toward his children.

"We have seen that lack of affection has played into the older children's life, especially Charles," Koenig told Express.

"In the next generation, you have much more hands-on – you still have nannies – certainly Charles and Diana were definitely much more hands-on parents."

She added how Prince Charles hugged children in public and did more as a parent. Also, Prince William and Prince Harry are less reliant on staff when it comes to looking after their children. In fact, both have talked about sleepless nights as part of fatherhood.

"You can be sure Prince Philip never got up to check on his kids at night," Koenig said of Prince Philip.

Just recently, an insider told Us Weekly that Prince Harry is very hands-on when it comes to Archie. He is "tone-deaf" but still sings lullabies for his son to make him sleep. Also, Markle does not need to ask him to do things for their baby because he just does them.

Prince Harry doesn't mind getting his hands dirty. He happily takes on diaper duties, burps Archie and cleans his spit-up without any complaint. Also, if Prince Harry has an early-morning engagement, he gets up at night to tend to Archie's needs.

Aside from the lack of affection, Prince Philip was reportedly furious with Prince Charles' weakness. He reportedly wanted the future king to be tough, but unlike him, the Prince of Wales was not abrasive and unemotional.

"The trouble is that the Prince of Wales is fundamentally a weak man, and that is what has incensed the Duke of Edinburgh over the years," Junor said in her 2005 book, "The Firm."

"He wanted a son in his own image – a tough, abrasive, plain-talking, unemotional man's man – but those qualities bypassed his first son and settled instead on his daughter."

Prince Philip and Prince Harry
Prince Philip and Prince Harry enjoy the atmosphere during the 2015 Rugby World Cup Final match between New Zealand and Australia at Twickenham Stadium on Oct. 31, 2015 in London. Getty Images/Phil Walter