Legendary tennis pros Venus and Serena Williams faced off against each other at the 2015 U.S. Open quarterfinals.  This wasn't a first. The matchup marked the 27th time the two have met directly in competition.  

Although the Williams' father has pointed out that he supports both of his daughters equally -- once joking with sports journalists that he'd place "50 pounds on each" -- the relationship has been reportedly, and understandably, fraught with tension. 

If you grew up with a sister or brother, you've likely experienced some form of sibling rivalry. Aspects of competition between siblings can, of course, be positive. Siblings may inspire each other. When it comes to running a business with family, siblings can often hold different roles -- depending on their various strengths and weakness. Each should contribute in their own right to the success of the company. 

"[Sibling rivalry] can be productive if they can identify that each has their own unique talent and skill," says Dr. Ellen Frankenberg, a family business adviser and psychologist based in Cincinnati, Ohio. 

The Williams sisters aren't the only example of successful, high-profile partnerships. Brothers Harvey and Robert Weinstein co-founded the eponymous film studio, The Weinstein Company, along with Miramax films (the former of which has grossed nearly $250 million in 2015 sales since January).

In a letter published by the Hollywood Reporter, Bob writes that the key to that success was having routine conversations: "Some people would say I deserve a lifetime achievement award just for talking to Harvey for that amount of time," he quipped. "Knowing Harvey, of course, he would probably find some way to accept the award on my behalf."

Still, the never-dull world of business touts many unpleasant examples, too. The German sneaker giant Adidas was also founded by two brothers, Adolf and Rudolph Dassler, who went so far as to request being buried on opposite sides of the graveyard. Their relationship had long been strained by the fact that they lived together, even when their wives didn't get along. Similarly, Jeppe Jarnit-Bjergso and Mikkel Borg Bjergso (also called "the Bjergso twins"), are separately the brains behind some of the world's most beloved and distinct craft beers (Evil Twin and Mikkeller). The brothers haven't spoken in over a year, as the New York Times reports. 

Roughly 85 percent of family businesses fail in the generational transition, according to consulting firm JSA Advising, which Frankenberg partly attributes to caustic sibling relationships. For one thing, entitlement doesn't work. It's unwise to place the first-born in charge by virtue of the fact that they're the eldest, and it's far more important that parents analyze each child's skill set.

If you're running your business with a sibling, here are some important points to be mindful of (especially if you'd like to avoid the fate of the Dassler brothers):

1. Put the past behind you (or, at the very least, make an effort to.) 

No matter how close you are to a brother or sister, you're probably holding on to childhood baggage.

The eldest child is often more responsible, since he or she would have been left in charge during the parents' absence. The youngest child, by contrast, is most likely to be an innovator. "Birth order is extremely powerful and sometimes underestimated," says Frankenberg. "Across many cultures, youngest children are more inclined to be risk-takers, because they have to find their own original way."

Parents are known to play favorites, at least inadvertently, so it's important that you and your sibling get past those related grievances before jumping into a business together. The psychological injuries of childhood may run deep, but that doesn't mean they can't be solved.

2. Communicate early and often.

To run a successful company, you'll need to communicate with your co-founder early on, and continue to do so daily. It's a good idea to slot partner meetings into your weekly schedule, since disagreements are bound to occur. 

Frankenberg develops what she calls "rules for fair fights" with her clients. 

"I think most of the conflicts may emerge not from any deep hostility but from failure to communicate clearly. One method is to use facts and feelings to confront," she explains. This means using concise statements such as: "You didn't show up for that client meeting. That made me feel very angry," rather than approaching the other person in a hostile manner. 

3. Recognize your different strengths, and give credit where credit is due.

Negativity may be unavoidable in some relationships, but there are ways to use the bad energy to strengthen a relationship. 

In fact, experts argue that negative interactions are actually "pro-social" cues, which allow us to recognize where the relationship stands to improve. But, of course, it's equally important for you and your co-founder to appreciate one another's contributions. 

Dr. John Gottman, an emeritus professor of psychology at the University of Washington, says that strong relationships can be quantified by a "magic" five-to-one ratio. For each negative interaction, you and your partner should have at least five positive ones. 

So, the next time you feel compelled to snap at your sibling, consider where they also deserve compliments for a job well-done.

4. Commit to looking at the bigger picture.

Ultimately, if you and your sibling share a common goal, your relationship is likely to be productive. 

As Serena Williams told the Los Angeles Times ahead of Tuesday's match-up: "We have proven you can be enemies on the court, and friends after." Frankenberg notes that for the Williams sisters, family loyalty supersedes individual achievement. 

Catherine Cook, 25, the co-founder and vice president of brand strategy at social media company MeetMe, agrees. Cook founded the company with her two brothers, Geoff (37) and Dave (27). "If you don't agree on the bigger picture stuff, then you're definitely not going to agree on the little picture stuff," she says.

Presently, Geoff serves as MeetMe's CEO. Dave exited the company as recently as two months ago, and now lives in Boulder, Colorado, where he and his sister attended college together. Cook says that she and her brother are very close. "We've had a very good time with the business," she adds. 

As the Williams duo hash it out on the court this evening, their rackets slamming against the same, battered ball, take time to reflect on the underlying teamwork that led to that very moment.