The recent flap over Republican presidential candidate Ben Carson’s life story and its accuracy offers a lesson that applies to anyone who’s ever recounted an autobiographical tale, including many other political candidates whose personal narratives include factual errors. That is, self-reported personal anecdotes are seldom entirely accurate and truthful, because they almost can’t be.

Here’s why.

When people talk about themselves and their pasts, they are motivated to both selectively remember and selectively disclose positive personal information.

As the authors of a recent social psychological study from the University of Illinois at Urbana-Champaign note, “Self-serving judgments, in which the self is viewed more favorably than other people, are ubiquitous.”

Conversely, people want to—and do—both forget about and fail to disclose negative personal information.

That’s not new with the case of Ben Carson: The effect of the favorability of information about the self on its likelihood of being recalled and shared publicly has literally been studied for decades. Sociologist Erving Goffman first published his classic book on people’s efforts to construct positive images and reputations, The Presentation of Self in Everyday Life, in 1959.

Second, we know from extensive research on eyewitness accounts of accidents and crimes that even when people have no incentive to be anything but accurate in their recollections, memory is invariably fallible.

As psychologists George Rahaim and Stanley Brodsky noted in a witness study, there exists “an impressive body of empirical data…arguing that eyewitness identifications and subsequent testimony are often unreliable.” And psychologists Deborah Davis and Elizabeth Loftus showed that memory becomes even more unreliable in the presence of media accounts and widely-disseminated rumors that further bias recall.

Third, as author Ben Dolnick perceptively noted, if someone retells a story often enough, the account becomes etched in the person’s memory. Therefore, the individual becomes incapable of distinguishing embellishments he or she may have consciously added in the beginning (to make a tale more interesting) from the true facts. Dolnick nicely described in his own life “how the things you write [or talk about] begin to blend with, and then replace, the things you experienced.”

Fourth, an article in Behavioral and Brain Sciences by a psychologist and an anthropologist demonstrates that self-deception is an adaptive trait. Self-deception is helpful in part because it permits people to display more confidence, and confidence attracts others. Self-deception also makes people more effective in deceiving others—your lying cannot behaviorally “leak” into inadvertent physical cues when you believe what you’re saying!

As an added bonus, when people believe the tales they tell, they have an easier time remembering the story. That permits them to tell the same thing consistently and also do so with more cognitive ease.

For these reasons, leaders’ stories about themselves are inherently and inevitably unreliable.

In the cases of Carson and the other candidates running for president, political aspirants for high office are often caught in their fabrications because they confront lots of fact-checking and public scrutiny by journalists and opponents.

Business leaders’ stories, on the other hand, typically face much less vetting. Consequently, business figures can claim positive relationships with family members and business associates even if the opposite is true. And they can (and do) embellish depictions of career successes with little fear that anyone will do much due diligence to ascertain the accuracy of the self-portrayals. In fact, because observers love heroic stories and want to believe in a just world, we are often complicit with the yarn-spinners in accepting the most positive portrayal of things.

There’s a big problem that comes from this myth-making: it leads to leadership case studies and biographies that are more myth than reality. But people seeking to learn how to be more successful in their own careers need accurate information in order to form accurate judgments. Moreover, because of the pervasive and almost inevitable inaccuracies in many leadership stories, these examples provide an exceedingly poor foundation on which to base a science of leadership.

As a social scientist and, more importantly, as someone trying to educate students in principles that explain human behavior, I believe that people can handle the truth and need facts and evidence to guide their decision making. Therefore, we need two big changes in the writing and speaking about leadership: We need much more due diligence on the stories proffered, not just by political candidates but by all leaders; and we need much less seeking of myths and inspiration.

When people stop buying into untrue—albeit uplifting—stories, they will be more likely to get the facts and insights that can form a better foundation for understanding and action.

Jeffrey Pfeffer is Thomas D. Dee II Professor of Organizational Behavior at the Graduate School of Business, Stanford University. His latest book is Leadership BS: Fixing Workplaces and Careers One Truth at a Time.