Barack Obama's sin was honesty.
Addressing a high school class in Manchester, N.H., earlier this month, the presidential candidate admitted that he was "kind of a goof-off in high school." He added that he had "made some bad decisions," and "got into drinking and experimented with drugs."
"There was a whole stretch of time that I didn't really apply myself a lot," Obama said. "It wasn't until I got out of high school and went to college that I started realizing, 'Man, I wasted a lot of time.'"
One might think he would get credit for having straightened up while he was in college. For many of his peers, the drinking and experimentation with drugs didn't let up during their college years.
But Obama was chastised by former Massachusetts governor and Republican presidential candidate Mitt Romney, who called the admission a "huge error."
"It's just not a good idea for people running for president of the United States, who potentially could be the role model for a lot of people, to talk about their personal failings while they were kids, because it opens the doorway to other kids thinking, 'Well, I can do that, too,'" Romney said.
Under the circumstances, Obama had little choice but to tell the truth. He had been guilty of committing candor when writing about his youth in his memoir, "Dreams from My Father," so it was on the record already.
Another Republican candidate, former New York Mayor Rudy Giuliani, had a more tempered response.
"I respect his honesty in doing that," Giuliani said of Obama. "I think that one of the things we need from our people who are running for office is not this pretense of perfection."
Giuliani, who has a colorful personal life of his own, probably is hoping the voters won't expect perfection from him, either. Romney, by contrast, whose personal life is as wholesome as skim milk, may have been trying to emphasize that he has nothing to hide.
But the clean-living Romney is more the exception than the rule. The Office of National Drug Control Policy reports that, in a 2005 survey, nearly 45 percent of the nation's high school seniors had used marijuana at least once in their lives. At least 80 percent of seniors have consumed alcohol, and 62 percent have been drunk at least once.
Is Romney saying that more than 60 percent of high school seniors are unqualified to ever run for president? Or is he just saying they should never reveal past drug or alcohol use?
The question about drugs and alcohol can come up in any campaign, especially since baby boomers started running for office. Presidential candidates have tried to finesse the answer in different ways.
Bill Clinton famously claimed not to have inhaled. As often was the case, Clinton may have been trying to have it both ways, hoping to appease the anti-drug voters while earning points with the Woodstock generation for at least trying to smoke pot.
George W. Bush confessed to "youthful indiscretions" and left it at that. This open-ended response leaves much to the imagination, although Bush was candid about his battle with alcohol that lasted well into middle age.
But Obama's willingness to come clean about his all-too-common "bad decisions" as a high school student might pave the way for some refreshing frankness from others running for public office. It also seems unlikely that Obama will become the role model for young drug users: He dresses too neatly, works too hard and has no visible tattoos.
Obama might be a role model of a different sort, that of a man who, while he may have stumbled as a youth, later righted himself and became a success. And there are thousands like him, people with youthful indiscretions who now are living responsible, productive lives.
As Giuliani said, we need to stop looking for perfection -- or the semblance of perfection -- from our candidates. What we need most from them is honesty.