Brotherly love has never been tested in the European Championship's 56-year history, but that will change on Saturday (June 11) at 10pm, Singapore time.
A pair of siblings will come up against each other for the first time when Switzerland take on Albania in their Group A opener.
Growing up, Granit and Taulant Xhaka were sometimes mistaken as twins as their Kosovo Albanian parents dressed them alike. Yet they would not be hard to differentiate at the Stade Bollaert-Delelis, with new Arsenal signing Granit, 23, in Switzerland colours and Taulant, 25, in Albania's kit.
Both were born in Basel, Switzerland and have featured on the same side. They played together at Swiss Super League outfit Basel for two years and represented Switzerland at various age group levels.
The Swiss FA persuaded midfielder Granit to stick with them but defender Taulant opted to represent Albania at the senior level.
Granit has already faced Albania twice in 2014 World Cup qualifying, with Switzerland winning both the home and away games. The brothers, however, have yet to face each other in a competitive international match.
"It will be tough not only against Taulant but also against Albania," Granit told Kosovo newspaper Zeri. "We played Albania a couple of years ago and it was really difficult. It will be tougher now that my brother has joined the Red and Blacks. However, we are professionals and have to play."
Swiss TV commentator Sascha Ruefer has doubted his professionalism in the past. With Switzerland leading Albania 2-0 in their home qualifier in 2012 , Granit was through on goal but sent the ball softly towards the goalkeeper. That prompted Ruefer to suggest that the midfielder passed up a goalscoring opportunity because of his Albanian roots.
The Swiss team, however, rejected those accusations.
Their father Ragip Xhaka - who moved to Switzerland in the 1990s to escape war in Kosovo - admitted there will be mixed feelings on Saturday.
"I am the happiest father in the world at this moment. Both my sons will be playing in the Euro championship," Ragip told Albania's Tirana Times. "I was a little upset that both Switzerland and Albania will be in the same group. I would have loved to see them play in the final but not in the same group."
More Euro bros
Thankfully for four other families, their support will be undivided throughout the tournament.
Everton striker Romelu Lukaku, 23, and brother Jordan, a 21-year-old defender, both made the Belgium squad.
And there could yet be more double joy for the Red Devils if midfielder Thorgan Hazard, 23, is called up from the standby list to join Chelsea forward Eden, 25.
West Bromwich Albion defender Jonny Evans, 28, is certain to have Blackburn Rovers midfielder Corry, 25, alongside him in the Northern Ireland camp.
There are also no doubts over which set of brothers will provide commentators with the greatest challenge when both are on the pitch. Russia's Vasili and Aleksei Berezutski, 33, are identical twins and both men play in defence. Former Russia coach Guus Hiddink reportedly once gave Aleksei the captain's armband just so he could tell the two apart. The CSKA Moscow duo were also part of the squad that made the Euro 2008 semi-finals.
Famous double acts
No fewer than 12 sets of brothers have graced this continental tournament over the years. Here is a look at five famous pairs.
Bernd and Karlheinz Forster (West Germany - 1980, 1984)
They were part of the West Germany squad that won the 1980 tournament, with defender Karlheinz starting in the final against Belgium. They would form a central defensive partnership at the World Cup final two years later, losing 3-1 to Italy. In Euro 1984, they failed to help their side get out of the group stages, but Karlheinz still made the team of the tournament.
Erwin and Ronald Koeman (The Netherlands - 1988)
They are the only brothers to start - and win - a European Championship final together. With Erwin in midfield and Ronald in defence, the Netherlands defeated the Soviet Union 2-0 in Munich. They worked together at Southampton for two seasons, with Erwin assisting his younger brother. Ronald guided the Saints to their best Premier League finish of sixth last season .
Brian and Michael Laudrup (Denmark, 1996)
Midfielder Michael missed Denmark's fairytale 1992 victory - which forward Brian starred in - after a disagreement with coach Richard Moller Nielsen over tactics. Although both players featured in 1996, Denmark could not progress into the knockout stages. They would end their careers on a high by making the 1998 World Cup All-Star team after leading Denmark to the quarter-finals. They are still regarded among the best footballers of all time.
Gary and Phil Neville (England - 1996, 2000, 2004)
No pair of brothers have featured in as many European Championships as the Nevilles. Phil was an unused substitute in the 1996 tournament, while Gary was a starter. The elder Neville, however, was suspended for the semi-final against Germany, which England lost on penalties. Gary and Phil started at right-back and left-back respectively in 2000, but England failed to make it out of the group stages. There was more penalty heartbreak for England four years later, when Portugal emerged from their quarter-final clash.
Frank and Ronald de Boer (The Netherlands - 2000)
The twins are widely recognised as one of the greatest siblings to play the game. They were the first brothers to win the Champions League together when they claimed the 1995 title with Ajax. Their Euro 2000 campaign was also unforgettable, particularly for Frank - albeit for the wrong reasons. In the semi-finals on home soil, the Oranje were held to a 0-0 draw by 10-man Italy despite being awarded two penalties in regulation. Frank's spot-kick was saved by Francesco Toldo while Patrick Kluivert hit the post from 12 yards out. In the penalty shootout, Frank saw another effort saved as the Netherlands fell 3-1.