Tomorrow is Super Bowl Sunday, which means we’re one day a way from crowning an NFL champion and, perhaps more importantly, learning which Harbaugh brother his parents are going to love best. In the unlikely case you hadn’t heard, for the first time in NFL history, the coaches of the two teams -- Jim Harbaugh of the San Francisco 49ers and John Harbaugh of the Baltimore Ravens -- are siblings.

Their parents may claim to love their children equally, but as we all know, there can be no sharing the Vince Lombardi trophy. In most sporting family feuds, there is one winner and one...their parents wouldn’t call them losers, so we won’t here.

To better understand what the Harbaugh family will be going through on Sunday, let’s have a look at some of the more interesting sibling acts in sports.

The Williams Sisters:

The Williams sisters, Venus and Serena, first began their winning ways on the WTA Tour as mere teenagers in the mid-to-late 1990s. While they both have had unbelievably successful careers, younger sister Serena has been the more consistent winner, with 15 Grand Slam singles titles to Venus’s seven. Serena also sits first on the all-time prize money list for a female tennis player, with more than $42 million (and counting) in earnings.

It should also be noted that Serena has a three-win edge in the more than 20 matches the two have played against each other.

It would be understandable if the two notoriously competitive players had a rocky relationship, but they are best friends who, when not playing at the same time, cheer each other on from the stands. They also make a great team on the court, with 13 Grand Slam doubles titles together, in addition to three Olympic gold medals.

Family Resemblance: The McEnroe brothers, John and Patrick.

Michael and Ralf Schumacher:

While the Williams sisters are an example of two siblings having similar success in the same sport, the Schumacher brothers are a study in the one star, one also-ran phenomenon. Michael Schumacher is considered one of, if not the, greatest F1 driver of all time with most wins (91), most overall championships (7), most points (more than 1,500) and most wins in a single season (13 in 2004).

Younger brother Ralf, on the other hand, won six races and finished his career with just over 300 points, and was forced to retire from F1 in 2008 when he couldn’t secure a team.

Still, Ralf and Michael are the only brothers who have won F1 races, and were the first brothers to finish first and second in a race (a feat they managed five times).

Family Resemblance: MLB Hall-of-Famer Cal Ripken, Jr., and his brother Billy.

The DiMaggio brothers (Vince, Dom, and Joe)

You knew there were three, right? In addition to Joltin’ Joe, there were Vince and Dom, and they all played centre field. Of course, Joe was the one with a Hall of Fame career and marriage to Marilyn Monroe, who could charge for autographs and people still loved him. He was an All-Star in all 13 of his major league seasons, hit .325 for his careeraverage and won nine World Series championships.

But his two brothers also played major-league ball, and enjoyed some success of their own.

Vince, the middle brother, played major-league ball for 10 years, retiring with a career .249 average. He made two All-Star appearances, but also led the National League in strikeouts for two seasons.

Meanwhile, Dom was the baby and looked the part at a mere 5’9” and barely 170 pounds. He was also one of the rare major-leaguers who took the field while wearing glasses. Despite his bookish appearance, Dom played 13 years in the majors entirely for the Boston Red Sox, batting .298 for his career and making seven All-Star appearances. He had a solid offensive career, but was also known for his base-running and fielding skills. He was also featured in David Halberstam’s book The Teammates along with Ted Williams, Bobby Doerr and Johnny Pesky.

Family Resemblance: The Molina brothers -- Yadier, Jose and Bengie -- all major-league catchers.

The Staal siblings (Eric, Marc, Jordan):

It’s fairly remarkable to have one child make it all the way to the NHL, but three of the four Staal brothers are enjoying solid pro careers. Eric, the oldest, is a Stanley Cup-winner with the Carolina Hurricanes and has served as the team’s captain since 2010. He was also part of Canada’s gold medal-winning team at the 2010 Vancouver Games.

Marc is an assistant captain with the New York Rangers and played alongside brother Eric in the 2011 All-Star Game. Marc finished the 2010-2011 season after a hard hit from Eric. However, post-concussion symptoms kept him from returning to game action until the 2012 Winter Classic against Philadelphia.

Jordan now plays on the same Hurricanes team as Eric, but was drafted by the Pittsburgh Penguins in 2006. He was nominated for the Calder Trophy, awarded to the league’s top rookie, but lost out on the prize to then-teammate Evgeni Malkin. He was part of the Penguins team that won the Stanley Cup in 2009, making him the second Staal brother to hoist the hallowed trophy.

Family Resemblance: Scott and Rob Niedermayer.

Leon and Michael Spinks:

The Spinks brothers both had solid professional careers, but it was Leon who famously beat Muhammad Ali in 1978 to become undisputed heavyweight champion of the world. Before going pro, Spinks won gold as a light-heavyweight at the 1976 Olympics, the same Games in which his brother, Michael, won the middleweight class.

While Leon’s career fizzled after he lost the heavyweight title to Ali in ’79, Michael was first light-heavyweight and then heavyweight champion. He only lost one fight as a professional, his last, when he was knocked out by Mike Tyson. Michael was inducted into both the International Boxing Hall of Fame and the World Boxing Hall of Fame.

Family Resemblance: Wladimir and Vitali Klitschko.