Ruaridh will attempt to help Scotland to successive wins in the RBS 6 Nations tomorrow as Paddy makes his debut for Ireland.
As the longer established of the two clansmen going head-to-head at Murrayfield there has, at times, been more than a hint of prodigy about the development of Ruaridh, the Glasgow Warriors stand-off. As a 20-year-old he bolted into the rugby public's consciousness with a stunning individual performance for Glasgow against Bath at The Rec and little more than a year later came the glorious day in his home city when his Test match-winning kick against Samoa had him crowned as king of Aberdeen.
Those were, though, five and three years ago respectively and, following the win over Italy a fortnight ago, Jackson himself said he has already had more than his share of ups and downs. Indeed, when Peter Horne, ahead of his first professional start at stand-off last night, explained what he had to live up to with the phrase "Jacko has been playing brilliantly all season," his words were those of a friend rather than an analyst.
The truth is more accurately reflected in the way that the Glasgow Warriors No.10 shirt went through a spell of changing hands as swiftly after matches earlier this season as those of Diego Maradona or Pele at football World Cups.
Which points us back towards the '70s. Drawing parallels with the music of that period one last time, the modern-day Jacksons have become more akin to the Osmonds when li'l Jimmy burst on to the scene seeking to steal the limelight from heart-throb Donny. Bursting with energy and confidence, Ireland's Paddy has, since a memorable debut appearance for Ulster in a win at the Scarlets two years ago, benefited from coming into a much more settled set-up.
That has contributed to far steadier progress as he tested another's family's loyalties to breaking point by effectively ending the Ulster career of Ian Humphreys, the younger brother of their director of rugby, David. It will be much tougher to establish himself in his national side considering that he is vying for his position with the best stand-off in Europe, Jonny Sexton's injury granting him this opportunity.
However, the Scots dare not under-estimate what the Test debutant brings. "What tends to happen when you lose a player at international level, everyone is probably not that closely aware of the skill-sets of the other players who replace them," said Scott Johnson, Scotland's caretaker coach.
"He's a threat because he's a good player. In two or three years we may be talking about Paddy Jackson as a quality 10 in world rugby, but at the moment no one knows who he is really. However, we know he's a threat and will be paying due courtesy to making sure he doesn't threaten us too much."
That response was prompted by a question from a reporter asking about the different challenge O'Gara would represent this weekend, albeit the veteran may also make a significant impact tomorrow. However, the risk Declan Kidney, the Irish head coach, has taken in opting for Jackson's youthful vigour ahead of O'Gara's wealth of experience is the strongest supporting evidence for Johnson's argument.
The youngster is merely the latest in a long line of authoritative Irish play-makers that most in Scottish rugby have eyed enviously since Craig Chalmers began to wane, but the Scottish Jackson has at times looked the most complete of the candidates to have emerged in the interim.
It is now seven years on from his Scotland sevens debut in Dubai, however, and he knows it is time for him to prove it. "It just shows when we have little games [among the Scotland squad] and get split into oldies and youngies and I'm in the oldies now," Jackson acknowledged with a rueful smile following the win over Italy.
"That's sort of sad but there is a transition. I'm having to take on more of a leadership role. I'm not the young guy in the squad and we've got younger guys pushing me. So there's a real youth and excitement in the back-line and we've got the old heads like Seany [Lamont] still showing he can mix it at Test level."
Of course, neither Jackson can shine without the backing band hitting the right notes. That has been a problem for Scots trying to take centre stage in recent times but all of a sudden it seems umpteen others are seeking to steal the show. Then again, as Tim Visser noted in midweek, some of the spectacular play is in danger of being covered up by ongoing deficiencies elsewhere.
The Scots know that, even including their John Beattie-inspired shock win over Ireland three years ago, there has been no better chance of a Six Nations Championship win over Ireland in a decade.
The absence through injury of first-choice players Sexton, Paul O'Connell, Stephen Ferris, Gordon D'Arcy, Tommy Bowe and Simon Zebo, as well as Cian Healy through suspension, would be far too much for many teams to cope with. However, Irish rugby has built a production line of superstars over the past decade which means they still have more British & Irish Lions involved than Scotland have sent on any of the combined team's last three tours; a contingent which includes Jamie Heaslip, Brian O'Driscoll, Rob Kearney, Keith Earls and O'Gara.
Is Paddy Jackson the next of them? By tomorrow evening we may have a much better idea, just as we will be closer to knowing whether Scotland's Jacko is going to be able to keep it all together for any length of time when under the spotlight.
The scene is set for a thriller.