The southpaw lightweight and her 29-year-old brother used to train alongside each other under Shane McGuigan but they are no longer in contact.

Even so, they share the distinction of being British boxing’s first ever brother and sister to hold world titles at the same time.

Caroline, 25, is The Ring, WBO and WBC lightweight champion while Daniel is currently in his second stint as world heavyweight champion after stopping Fabio Wardley for the WBO belt in May.

On their dual position as world champion, Dubois (14-0-1, 5 KOs) told The Ring: “It's hard to get your head round it when you think of how far women's boxing has come. I don't think that was even a possibility maybe 15 years ago.

“I don't know if there were many women world champions, period but it just shows the progression of the sport, the evolution. I'm proud."

Dubois (23-3, 22 KOs) is The Ring’s No. 1 heavyweight following his come-from-behind victory over Wardley, where he climbed off the floor twice within the first three rounds to win by 11th-round TKO at Co-op Live Arena.

Oleksandr Usyk remains The Ring champion despite his decision to relinquish all his sanctioning body titles earlier this year.

The Ukrainian great, who has cemented his place as the best of his generation by twice beating Dubois, Tyson Fury and Anthony Joshua, has declared that he wants just one more fight before he retires.

And, once he decides to hang them up, Dubois believes her brother will emerge as the best in the world.

“The heavyweight division is probably the best it's been for a very long time since the days of Evander Holyfield, Mike Tyson and Lennox Lewis,” she said.

“Right now, there's some serious, crazy, dangerous names in the mix. There’s Moses Itauma, Filip Hrgovic, Agit Kabayel ... and the best thing is that Daniel's up there. He's one of the best names.

“He's definitely going to be the future face of the heavyweight division for sure.”

During an interview with the BBC in April, Dubois explained why she decided to leave the family home where she was raised. A row with her father, Stan, led to her decision to depart two years ago and she has not spoken to him or Daniel since.

At the time, Daniel left McGuigan and joined up with Don Charles while Caroline stayed at the east London gym. She has since left and worked with Manny Robles for her last fight.

Despite the separation from her two-time world heavyweight champion brother, she is still pleased about his success.

She said: “I'm happy to see him kicking ass and doing his thing.”