If ever there was a safe space for Ben Affleck to discover and disclose something as grave as the revelation that his ancestors once owned slaves, it would be PBS.

“Finding Your Roots” is a show about history and genealogy, completely devoid of sensationalism. The draw is the famous people who agree to reveal their family’s lineage as they learn about it.

Affleck’s family used to own slaves, a fact that he sought to cover up before his episode aired, according to e-mails from the Sony hack, uploaded last week and cataloged into a searchable database on the WikiLeaks site.

In a July e-mail to Sony Entertainment chief executive Michael Lynton, “Finding Your Roots” host Henry Louis Gates Jr. wrote, “Here’s my dilemma: confidentially, for the first time, one of our guests has asked us to edit out something about one of his ancestors — the fact that he owned slaves. Now, four or five of our guests this season descend from slave owners, including Ken Burns. We’ve never had anyone ever try to censor or edit what we found. He’s a megastar. What do we do?”

In the thread, Gates also refers to the “megastar” as “Batman.”

Now that the e-mail chain is public, everyone knows about Affleck’s ancestry trivia, he has zero control over the story, and he’s become the latest celebrity to experience the Streisand effect.

Whatever the bad news is, cover-ups are almost undoubtedly always worse. What’s perplexing is why Affleck would want to conceal something that happened before he was born.

This is a good example of the casualties of the big Hollywood PR machine. Real people are replaced by aspirational humanoid creatures with charming, Q-scored imperfections who can sell movie franchises, and anything remotely negative must be hushed out of existence. It’s what makes the gossip so compelling when we discover stars behaving in stark contrast of their carefully curated public characters.

Heaven forbid that the public discover that Affleck’s family used to own slaves and then decide that that’s reason enough not to see “Batman v Superman: Dawn of Justice.”

One of Germany’s great novelists, the Nobel-winning Günter Grass,  who died last week, came under fire when he admitted in his 2006 autobiography that he served in the Waffen SS during World War II. But unless Affleck is remarkably well preserved, like modern-mystery-of-science-and-medicine well-preserved — in which case he is hiding a much bigger, much more interesting secret — we know he wasn’t a Confederate general.

Affleck was not the first celebrity participating in “Finding Your Roots” to learn that his ancestors owned slaves: Anderson Cooper learned that, too, and they kept the revelation in the show. In fact, Cooper’s ancestor, Burwell Boykin, was killed by one of his slaves, who beat him to death with a farm hoe.

When Gates asked whether he thought Boykin deserved to meet his end so violently, Cooper responded, “Yeah, I have no doubt.”

So why hide the truth, especially when it could have been used to illustrate a journey within Affleck’s own family, from an ancestor who owned human chattel to Affleck’s mother marching for the civil rights of their descendants?

Historical connections to slavery are part of the American experience. We’re still exploring its legacies and the way they manifest themselves, from Ta-Nehisi Coates’s “Case for Reparations” to characters on Starz’s “Survivor’s Remorse” making their own comically ill-informed case for personal reparations.

But not even esteemed PBS is immune to the Hollywood PR machine. Removing content from the episode at Affleck’s request was a violation of PBS rules. Gates explained the decision in a statement:

The mission of “Finding Your Roots” is to find and share interesting stories from our celebrity guests’ ancestries and use those stories to unlock new ways to learn about our past. We are very grateful to all of our guests for allowing us into their personal lives and have told hundreds of stories in this series including many about slave ancestors — never shying away from chapters of a family’s past that might be unpleasant. Ultimately, I maintain editorial control on all of my projects and, with my producers, decide what will make for the most compelling program. In the case of Mr. Affleck — we focused on what we felt were the most interesting aspects of his ancestry — including a Revolutionary War ancestor, a 3rd great-grandfather who was an occult enthusiast, and his mother who marched for Civil Rights during the Freedom Summer of 1964.

This dance with celebrities is representative of a bigger ongoing negotiation for the famed public TV station. The success of shows such as “Downton Abbey” and “Sherlock” have meant a huge boost in ratings, especially among younger viewers, and an expansion of “Masterpiece” programming thanks to additional sponsorship. For celebrities, the appeal of PBS is simple: It offers gravitas and legitimacy — just look at Jeremy Piven, who stars in the “Masterpiece” vehicle “Mr. Selfridge” and was recently on the public radio quiz show “Wait Wait … Don’t Tell Me!” Piven has effectively used “Selfridge” to rehabilitate his image after exiting his Broadway show “Speed-the-Plow” early, citing a dubious mercury poisoning ailment.

But there are those who worry that as the network finds success with a younger viewership, it loses sight of its mission as a provider of programming in the public’s interest — programming that’s generally less star-studded and grabs fewer eyeballs. The latest wrinkle in this is a conflict involving independent filmmakers who are worried about WNET (one of the nation’s flagship public television channels and one that sets trends for others) trying to move the documentary series “Independent Lens” and “POV” to a secondary channel and out of prime time. WNET also co-produces “Finding Your Roots” with Gates.

A stain on the editorial integrity of a show such as “Finding Your Roots,” to some, would signal a move toward fluff and away from the standards for which PBS is known. And Gates was acutely aware of this.

“Once we open the door to censorship, we lose control of the brand,” he told Lynton.