Mixed messages are a fact of life in American culture. We tell kids to delay sex, even as the media uses it to sell them music and shampoo. We preach healthy eating, even as the marketing industry herds them through a ubiquitous gauntlet of junk food.

Sorting out the negative influences is a constant battle. If you doubt it, look at the statistics on STDs and obesity.

Now we are knee deep in mixed messages surrounding Hillary Clinton's presidential bid, and there are some doozies in there for young girls considering their place in the world.

On the one hand, we've got the historic first of a woman with a real shot at a major party nomination. On the other hand, she's being targeted -- not by her opponent, but by the punditocracy -- with the same old double standard.

There are substantive reasons to like or dislike Mrs. Clinton aside from her gender, but there is more to the attacks against her than Clinton-specific animosity. A lot of it has to be chalked up to sexism, pure and simple.

A case in point: Nobody accused Mitt Romney of "pimping out" his sons when he sent them out on the campaign trail. But a televison loudmouth felt perfectly free to level exactly that charge against Mrs. Clinton when her daughter, Chelsea, waded into the fray. He apologized, but the stench lingers.

In any given week, Mrs. Clinton is portrayed as a veritable Sybil of multiple personalities. If she shows any emotion, she's attacked as weak or manipulative. If she stays on message and shows no emotion, she's cold and calculating. If she laughs -- or, as some like to put it, "cackles" -- she's acting. If she stares down critics or fires back, she's a scary witch, or a word that rhymes with it. Most of all, she's lambasted with the ultimate oxymoron: She's too political for politics!

When a heckler waves a sign at a Clinton rally that says "Iron my shirt," the commentators chortle. Likewise when Carl Bernstein says she has thick ankles, and when Chris Matthews repeatedly raises the specter of male politicos being "castrated" by the likes of Mrs. Clinton and Nancy Pelosi.

Every time some media gasbag goes off on these toxic rants, every time one chimes in on Mrs. Clinton's marriage, wrinkles or cleavage, or purports to analyze her heart, soul or psyche instead of her record, experience or policies, I can't help wondering: How many teenage girls have observed these deeply personal, sexist attacks and concluded that their parents have been lying to them, or at least shading the truth, about gender equality in America?

Of course women are doing better by many measures than in the past. And of course the mere fact of Mrs. Clinton's candidacy -- and of Barack Obama's, as well -- is testament to how far the needle has moved.

But any time the old barriers crumble, an angry backlash ensues. And the higher one rises in the political firmament, the clearer the site lines for the media snipers. Any candidate who is a "first" is going to draw a more intense barrage and need a higher threshold of pain.

Mr. Obama has avoided this to some degree through personal magnetism and charm, and the tacit understanding that in 2008, bald-faced race-baiting is not acceptable (Gov. Ed Rendell's statement about Mr. Obama's chances in Pennsylvania was about the voters, not the candidate). We'll see how long that lasts if he gets the nomination.

For Mrs. Clinton, on the other hand, the snipers were a pre-existing condition. The right wing's Pillory Hillary industry ran full bore for all eight years of Bill Clinton's presidency, and the Monica scandal gave them an especially choice opening. The rest of America gamely followed.

Women and men alike wallowed in theories about why Mrs. Clinton stayed with her husband and what that said about her. Having no personal knowledge of the couple's "psychodrama" didn't stop a lot of folks -- media folks in particular -- from chiming in.

Some said it was a character flaw for her to stick with her marriage (although if she'd left him, they'd have attacked her lack of family values). She was portrayed, variously, as power-hungry, in denial, co-dependent, an enabler, a victim, a martyr, a cold-blooded lawyer. It's amazing that the nation's universities didn't bestow a blanket honorary doctorate of psychology on all the commentators.

For all the griping and sniping, Bill Clinton remained a popular president, and New York voters liked Mrs. Clinton well enough to send her to the U.S. Senate. She knew what she was in for when she entered the race for president; she's said for years that she's a "Rorschach test" for voters because people project onto her such a wide range of emotional responses. But she chose to forge ahead, and probably isn't at all surprised by the attacks.

That doesn't mean they should pass unremarked. And in some quarters, they haven't. My own high school senior, who likes both Democratic candidates, was seething after a panel of blowhards -- male and female -- disgorged a stream of personal invective at Mrs. Clinton earlier this week. To quote my daughter: "I hate this! She can't win with them no matter what she does!"

The voters have been known to repudiate the punditocracy in the past, and whether Mrs. Clinton can win the nomination is still an open question. But in the meantime, young women and teenage girls who are paying attention are getting a real wake-up call. All those tiresome stories from their mothers and grandmothers about the bad old days of barriers and double standards are suddenly taking on contemporary meaning.

If they've taken for granted the progress so far, this is evidence that those successes have to be defended and advanced by every generation. That doesn't mean they have to like or support Hillary Clinton. It does mean that for all the gains women have made to this point, the march for real equality still needs them.