Friday, May 15, marks a big day in the De Boer family, as twin brothers Frank and Ronald turn 50.
The Dutch siblings are arguably the most successful footballing twins of all time, having amassed hundreds of caps and dozens of trophies over the course of their intertwined careers.
There have been many other twins to have both made the grade as professional footballers, and here are just a few of the more notable examples.
1. Rene and Willy van de Kerkhof
The tousle-haired Brazilian full-backs made their names at Manchester United after signing from Fluminense together in 2008. They spent the next six years playing alongside one another before going their separate ways. They are both now in France, with Rafael at Lyon and Fabio playing for Nantes.
The near-identical utility midfielders came through the ranks together at 1860 Munich as kids before parting ways -- Lars to Bayer Leverkusen and Sven to Borussia Dortmund -- only to be reunited again in 2017 when the latter joined his brother at Leverkusen.
5. Halil and Hamit Altintop
Halil was a decent winger, while Hamit -- who is 10 minutes older -- was a gifted midfielder who won the 2010 Puskas Award with a thunderous volley against Kazakhstan.
The Olssons' brother-in-law is former NBA star Dirk Nowitzki, who married the twins' older sister Jessica in 2012.
8. Radja and Riana Nainggolan
Paul's older twin siblings may not quite enjoy his level of celebrity, but both are serviceable players who have represented Guinea at international level.
10. Ray and Rod Wallace
The Wallaces were the very first twins to play in the Premier League, with both playing for Leeds in the early 1990s.
Ray bowed out after just seven appearances, but Rod went on to score 45 goals in 197 top-flight games.
However, the story of the Wallaces actually started at Southampton, where older brother Danny broke into the first team in 1980. Ray and Rod then both signed for the Saints, and in October 1988, against Sheffield Wednesday, all three were on the pitch at the same time. It was the first time three brothers had played for the same team in 68 years.
11. Dean and David Holdsworth
The Holdsworths started out together as youngsters at Watford in the late 1980s before their careers took separate paths. However, they did reunite at Bolton in the 1990s for a very brief time before both moving into lower league management.
12. David and Philipp Degen
The brothers were selected to represent Switzerland at the 2006 World Cup. There's not a lot to split their careers, with both winning three Swiss league titles at Basel (two together), though Philipp has over twice the caps. Philipp probably edges it, though, having (barely) played for Liverpool and spending three seasons at Borussia Dortmund.
13. Thomas and Andreas Ravelli
Former goalkeeper Thomas is revered as one of Sweden's greatest ever players, while Andreas managed to muster a perfectly respectable 41 international caps of his own.
Both the sons of a professional footballer, Ramiro (the centre-back) is the one who used to play for Everton, while Rogelio (the striker) has been banging in the goals for Monterrey for the past four years -- to the point where he's actually their second-highest scorer of all time.
15. Rachael and Megan Rapinoe
Of course, Megan is the iconic two-time World Cup-winning star of the USWNT, as well as the recipient of the 2019 Women's Ballon d'Or and former Best FIFA Women's Player award winner.
You may not know that her twin sister, Rachael (pictured above with Megan's partner and WNBA legend Sue Bird) also represented the United States at under-23 level and spent a season playing pro football in Iceland with Stjarnan Women in 2010.