WASHINGTON -- Redemption is in the air, we keep hearing. Americans don’t care about a person’s sex life because, well, they have one, too, and, hey, we all have weeds in our garden.

Indeed we do, but not all sins are created equal. And though we are quick to forgive the repentant -- and do believe in second chances -- we also seem to apply different standards to men and women.

There may be legitimate reasons for this, though they aren’t likely to be popular. We expect more of women because civilization depends on it. For centuries, we’ve relied on women to rein in men’s passions, to channel men’s libidos in constructive ways -- building suspension bridges, for instance.

Our available data on the double standard is limited in part because fewer women than men are in public office. But also, in the main, women don’t behave as men do. The male libido is simply greater, which accounts for both the Sistine Chapel and Attila the Hun.

Popular culture seems determined to change this timeless truth by encouraging girls to be more like boys, and vice versa. The stakes are clear: if girls can be portrayed as just as bad as boys, then males have no obligation to mitigate their natural dominant, exploitive inclinations.

There has been some measureable success in this regard. Recent reports indicate that college-age girls are increasingly promoting casual sex these days. Even so, no woman in public office thus far has texted her Very Own Self to strangers, as Anthony Weiner did.

If there were such an individual, it is certain that she would not be forgiven. Imagine any woman in public office today comparably exposing herself. Redemption? No. Way.

The double-standard test is (sort of) playing out in New York City’s comptroller race, where erstwhile madam Kristin Davis is one of the candidates running against former Gov. Eliot Spitzer (my former TV colleague), to whom she claims to have provided escorts. Judging by Davis’ own commentary, however, this is more comedy than contest: “This is going to be the funnest campaign ever.” Whatever her talents, Davis is obviously no match for the former “sheriff of Wall Street.”

But were they equally competitive otherwise, it’s a near certainty that voters would be less willing to forgive the woman who provided services than the man who procured them. Thus it has always been.

More on this in a moment, but first a quick visit down South where Mark Sanford orchestrated his own forgiveness, winning election to Congress where he served before becoming South Carolina’s governor and Argentina’s ardent visitor.

Sanford won despite having wept his way through a cringe-inducing confession and recently had been accused of trespassing on his ex-wife’s property. Why did voters elect such a man?

First, because his weaknesses notwithstanding, Sanford is admired by conservatives for his cost-cutting history. Second, his offense, though it included abandoning the state for several days and lying about it, involved something less tawdry. He simply fell in love.

Importantly, he and his now-fiancée were co-equals in a relationship absent any hierarchical power. This is key to the real issue afoot. The current redemption fest, including the San Diego mayor who harassed women in his employ and thinks an apology ought to wrap things up (and lest we forget Bill Clinton’s imbroglio with an intern), isn’t about hypocrisy or crassness or cavalier apologies.

It’s about power.

One could argue that Weiner was merely flirting with Twitter “friends” who, presumably, were interested in his bona fides. Then again, Weiner was a congressman, not a frat boy on spring break. There really is, or should be, a distinction.

And though purchased sex implies a mutually agreeable, if illegal, transaction, the power differential between an elected official and a prostitute is explicit.

But turn on the TV and you’ll hear that no one really cares anymore because it’s “only sex.”

If ever two words were mismatched.

There is never, ever “only” sex, especially for women, who are, indeed, different than men. We can argue otherwise until all the little dissertations cry “oui, oui, oui” all the way home. But the fact that the double standard persists in the human psyche, not to mention nature, demonstrates this unfair truth. This is why we have laws to level the playing field.

Perhaps the next step in this evolutionary process is not to make women more like men to neutralize the double standard but to place more women in public office, the better to demonstrate the behaviors necessary to maintaining a civil society.