Story highlights "My intention was not malicious," MSNBC hosts tearfully says

"The folks at MSNBC made a big mistake and they apologized for it," Romney says

Harry Truman once threatened a critic who wrote his daughter "cannot sing very well"

Harris-Perry's apology makes one rule clear: the kids are off limits

MSNBC host Melissa Harris-Perry chastised her guests for being too serious just before the controversial segment about former Republican presidential nominee Mitt Romney's adopted black grandson.

A source who was in the studio during the show told CNN that before the offending segment, the comedians were urged off the air to be funnier. The source asked not to be identified.

Later in the show, Harris-Perry told viewers the panel of comedians would "be forced to drink during the commercial so they can get their funny back."

"My intention was not malicious, but I broke the ground rule that families are off limits, and for that I am sorry," Harris-Perry said Saturday.

The apology comes weeks after MSNBC host Martin Bashir lost his job because of remarks about former GOP vice presidential nominee Sarah Palin.

Controversial comments by journalists about an American politician's family are not new. Harry Truman threatened physical violence against a Washington Post critic who famously wrote in 1950 that the president's daughter "cannot sing very well."

While Margaret Truman put herself into the public eye with her performance, Romney's grandson Kieran James only sat on his grandfather's lap for a family Christmas card photograph. And this instance involved race.

JUST WATCHED See Romney's reaction to MSNBC apology Replay More Videos ... MUST WATCH See Romney's reaction to MSNBC apology 00:43

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JUST WATCHED MSNBC pokes fun at Romney family photo Replay More Videos ... MUST WATCH MSNBC pokes fun at Romney family photo 06:45

Ridiculing transracial adoption?

Harris-Perry asked her panelists to come up with captions for the photo of Romney, his wife and their 21 grandchildren, all white except for Kieran.

Comedic actress Pia Glenn sang a Sesame Street song: "One of These Things Is Not Like the Others."

Comedian Dean Obeidallah joked that the photo "really sums up the diversity of the Republican Party."

Harris-Perry described the baby as "gorgeous" and suggested Kieran could someday marry North West, the daughter of Kanye West and Kim Kardashian. "Can you imagine Mitt Romney and Kanye West as in-laws?" she joked.

Unlike Truman and the critic, Romney quickly forgave Harris-Perry. "People make mistakes, and the folks at MSNBC made a big mistake and they apologized for it," Romney said in an interview on "Fox News Sunday." "They apologized for it. That's all we can ask for."

Daily Beast political columnist Sally Kohn, a guest Sunday on CNN's "Reliable Sources," blamed the growing competitiveness and immediacy of media today for the increase in such incidents.

"There's always this incentive to say something that's newsworthy, attention-getting, but it's real easy to cross the line into offensive and stupid," Kohn said. "And that's a split-second judgment sometimes."

The punch lines drew fire from critics who said they disrespected transracial adoptions, which the Department of Health & Human Services says make up 40% of all adoptions in the United States.

"Allow me to apologize to other families formed through transracial adoption because I am deeply sorry that we suggested that interracial families are in any way funny or deserving of ridicule," Harris-Perry said in her Saturday apology.

Harris-Perry, who is a political science professor at Tulane University, was surrounded by four comedians and no professional journalists. The live, unscripted show, which she said was her second annual "Look Back in Laughter" edition, seemed more like a night at the improv than a cable news program.

"This is the show where we dispense with the serious and sober coverage of the year in politics," she promised viewers. They would look back on "some of the political absurdity of 2013 with the ridicule and mockery it so rightly deserves."

Harris-Perry delivered an opening monologue loaded with obvious sexual puns about the Anthony Weiner sexting scandal.

Comedian Judy Gold joked about Sen. Ted Cruz, saying it was scary that the Texas Republican had daughters. Other comments came about the daughters of "rich, white Republicans."

The mandate for more punch lines was made clear by Harris-Perry after one somewhat serious segment.

"My comedians are all going to be forced to drink during the commercial so they can get their funny back because they've got real serious about sexism and feminism," the host said.

"We are basically ratings whores," Harris-Perry added.

Politico media reporter Dylan Byers said the MSNBC brand has been damaged by these controversies, considering the channel was "supposed to elevate the discourse" with smart, well-educated progressives who "lean forward."

"It's leaning backward and it's totally, it's not what MSNBC, I think, was supposed to be about originally, and I think it's doing real, severe damage to the brand," Byers said on CNN's "Reliable Sources."

Boston radio host Callie Crossley told "Reliable Sources" that Harris-Perry's brand has been damaged by the controversy as well. "Her brand is to exactly be on top of the kind of ignorant and other kind of racist commentary."

Blurry ground rules

The Society of Professional Journalists has a code of ethics that says journalists should "use special sensitivity when dealing with children" and "show good taste." Students learn it in most journalism schools.

But the rule book in the rough-and-tumble world of politics and media is an unwritten common law of precedents that evolves partly through apologies, resignations and firings. Harris-Perry's apology makes one rule clear: The kids are off limits.

There are exceptions to the rule, such as when politicians decide to use family members to win support.

The campaign of New York's new mayor, Bill de Blasio, prominently featured his biracial family in commercials and campaign events. Teenage son Dante appeared in his own ad highlighting his father's stance against "stop-and-frisk." Dante and his Afro-style hair became a social media sensation and is credited with helping his father surge to the top of the polls last year.

"His family, just because of the racial mix, represents a big and increasingly large part of the city and speaks to certain sensibilities," said Harold Ickes, a veteran Democratic Party operative who advised the campaign and has known de Blasio for two decades. "The family is very important to Bill. ... From the outside, this family represents a part of the city not represented in city government."