They say that blood is thicker than water. It is the lifeforce that binds us together, the fuel that drives us forwards - the elixer of existence and its limitless possibilities.
There is clearly something about the Dubois family though that takes this maxim and pushes it to the limits of success, a hunger and verve that seems relentlessly undimmed.
One year ago, brother Daniel and sister Caroline were contenders to some of the biggest thrones in boxing. Now, both sit upon it themselves, respective world champions.
Their place as one of modern boxing's first families is on its way to being firmly cemented. Both hold titles from major governing bodies. Both have delivered successful defences.
But does it end there? Can it even end there? At 27 and 24 respectively, the pair are in the prime of their sporting life, or perhaps not even at the peak of their powers.
Boxing can be a fickle discipline. One missed swing, one loose jab, one slip on the canvas is all it can take to unravel decades of dreams and ambitions.
Yet there is a steeliness behind the eyes of both siblings - and it is that unshakeable self-belief they have honed over the past few years that may set them up for further greatness.
Matt McNulty/Getty Images
Last Friday, on March 7, Caroline stepped into the ring at the Royal Albert Hall, part of a history-making bill for women's boxing topped by Natasha Jonas and Lauren Price.
It marked a quick return to the ring for the star, who had only managed three rounds in her first full defence of the WBC lightweight title against Jessica Camara in January.
There, an accidental cut from a clash of heads had seen the contest waved off as a technical draw. Dubois has already dropped her opponent and looked on the way to a win.
Few boxers want a draw on their records, no matter how you cut it, especially one that is ruled so early in the fight. Contenders can be left smarting by the brackets for years.
A quick return was needed to keep the momentum going. Dubois was keen to seize on the work she had put in since Katie Taylor had stepped aside to allow her elevation.
Bo Mi Re Shin was a rank outsider, and even as she managed to take her foe the distance, there was little to suggest she was ever close enough to seriously threaten an upset.
Dubois was duly crowned winner by majority decision, to move to a 11-0-1 record that further underlines her talent since turning professional only three years ago.
It befits her ambition - already this year, she has outlined triple-tier goals, telling BBC Sport: "I want to be undisputed in three weight divisions and then retire [...] before 30."
That leaves six years on the clock, with a desire to complete the first division before 2025 is out - a tall order when all three other major belts are held by three other fighters.
But with her bravado, you would be a fool to bet against her making further strides towards conquering the division before Auld Lang Syne rings out in Greenwich on January 1.
Mark Robinson Matchroom Boxing.
Caroline was not the only Dubois who ended 2024 on a high note, and was then forced to adapt in 2025 - except for Daniel, the plans remain in a fascinating state of flux.
The elder Dubois delivered arguably the most ruthless performance of his career last September when he stopped Anthony Joshua inside five rounds at Wembley Stadium.
It was a brutal, bruising display of raw power, and even when wobbled in the last round by his more experienced foe, he came back to finish the job in blockbuster fashion.
Plans for a rematch fell through when Joshua was deemed not ready for a February fight, with Dubois chasing a bout that month to reportedly circumvent a mandatory defence.
Former WBO heavyweight champion Joseph Parker stepped in to challenge for the IBF title instead - and then, amid fight week in Riyadh, the bout was scotched through illness.
It took the wind out of the sails for what had been a hotly anticipated contest - and now, Dubois faces lingering questions over his next steps in a fluctuating heavyweight division.
Tyson Fury's abrupt retirement has removed one chess piece from the board. Joshua is back in the frame to chase a possible revenge mission. Parker has unfinished business.
But for Queensberry Promotions boss Frank Warren, only a rematch with Oleksandr Usyk - to become undisputed champion no less - can be the bout that Dubois should take.
"It’s a no brainer. I don’t get where anybody’s brains can be on this,” he was quoted. "He [ain’t] ducking anyone.
"The objective of the fight that didn’t happen was that the winner would face Usyk. So if the Usyk fight can be made, it will be made. We’re talking.”
There are logistical hurdles here, namely that Parker - who has tirelessly worked his way back to contender status - may be left waiting once again for a shot at two-time status.
Then there is Usyk. Spotted ringside with Dubois absent last month, the Ukrainian laughed it up with ex-rival Joshua as the two snapped selfies and seemingly had a great time.
Questions have followed him since defeating Fury for a second time over his future, and while he has appeared open to another dance with Dubois, it is far from an assured deal.
Like his sister, Daniel could end 2025 in the undisputed conversation. But the pathway to such success might be more tangled by the slate of contenders than many realise too.
James Chance/Getty Images
Then there is the relationship between the pair too - or rather, the current lack of it. Ever since a fallout with their father in 2023, Caroline has been estranged from her sibling.
She was notably not in attendance for his victory over Joshua, and speaking before her bout with Camara, queried why nobody asks her brother why he does not watch her bouts.
“Daniel hasn’t come to any of my last four fights, and yet no one asks him that question," she was quoted then by the AP. "He’s not at this fight, he won’t be at the next fight."
With careers both under the spotlight of the sporting world and all that comes with success at the highest level, the pair's connection will be one probed again and again and again.
Whether they can bridge the differences is something to be dealt with between them. Family ties, for many, are a private and personal matter, even as the world speculates on it.
But irrespective of reconciliation, there is no denying that both siblings are laying serious claim to success with their surname across their respective divisions right now.
The path ahead is far from clear for either fighter - but at the same time, the opportunities lie at their feet to seize 2025 by the gloves and absolutely unload in the ring.
Caroline has already thrown down the gauntlet twice this year. Now, it will be Daniel's turn to pick it up and carry forward his dream, as both continue to shoot for the stars.
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