Do singles have better sex lives? Are women born to be married and monogamous? 20/20 takes a look at dating, mating and our sexual side -- and 10 things our mothers never taught us in "Sex: Myths, Lies and Straight Talk."
20/20 put the following popular notions about romance and sex to the test and found some surprising answers.
1. Are Short Men at a Disadvantage in Romance?
Ask any woman: Men who are 5-foot-9 -- that's average -- or taller clearly have it over their more compact cousins.
And it turns out a man's height has always helped him get to first base. Nearly 10 years ago, 20/20 concocted a test to illustrate an indisputable rule of love: height matters.
20/20 recruited men tall and short and put them in lineups behind a two-way mirror, then invited groups of women to look at the lineup and choose a date. The women were told various positive things about the shorter men -- the men were described as having interesting careers, impressive educational pedigrees or a lot of money. The women always chose the tall men.
Nothing succeeded in making them prefer the shorter men. One woman even suggested that 20/20 describe the tall men as "murderers" to even the odds for the shorter men in the test.
Professor Allen Mazur of Syracuse University, who at 5-foot-7 stands a few inches below average himself, did a study that found taller men are likely to marry more often and have more children. Mazur said one possible reason for his finding is that "taller men, by virtue of being more attractive to women, perhaps have more opportunities with women other than their wives, which leads to a breakup of marriage, which leads to a remarriage to a younger woman, which leads to another child."
Would it be fair to say from the study that it seems that taller men were hot and the shorter men were not? "That would be an inference. You could also infer that the shorter men are better husbands, and they have more long-lasting marriages," Mazur said.
2. Do Blondes Have More Fun?
From Mae West to Marilyn Monroe to Farrah Fawcett to Pamela Lee Anderson, blondes have embodied the notion of the sex symbol. But it was a Clairol hair color advertisement that raised the big question: Do blondes really have more fun?
Do they? 20/20 hired two actors to go platinum to find out, and came up with a very unscientific test using hidden cameras.
Actress Diedre Lorenz found lots of people willing to help a fair-haired maiden in distress. Some went beyond the call of duty, offering their phone numbers and to take her out for a drink.
Lorenz said she doesn't typically get the sort of attention that she received with her blond tresses.
What about a platinum-haired man? Actor Jake Mayers gave it a shot and said he felt "sexier, and I do feel more attractive."
While surveys say blondes are often perceived as "ditzy" but "glamorous," brunettes are seen as "competent" and "trustworthy."
Posing as a dark-haired tourist, Jake felt he got less action but more respect.
As a brunette, Deirdre felt invisible. She got dramatically less attention than she did with her blond hair.
"Men basically were throwing their phone numbers, begging me for my phone number, wanted to take me out sightseeing, take me for drinks," she said. "Today, not an offer. Literally, I did not have an offer."
If it's any consolation, studies show women are nicer to brunettes.
Research shows men are twice as likely to help someone out if she's a blonde. Our experiment found blondes certainly turn more heads, and that may be the fun a lot of people are looking for.
But our testers say fun, like beauty, is in the eye of the beholder.
"If you want a lot of glances, blondes. If you want something deeper, perhaps brunettes," Lorenz said.
And Mayers? As a blond he felt attractive and sexy, as a brunet he said he "felt real."
3. If You Talk to Kids About Sex, Will It Make Them Want to Have Sex?
It's logical for parents to think that if they bring up to the topic of sex with their kids, their kids will think, "Oh, I guess it's time for us to do it!"
How do we explain intercourse, unwanted pregnancies and the risk of sexually transmitted disease to kids? The old conversation about birds and bees just doesn't cut it today.
There used to be so much ignorance about sex. Back in the 1800s even experts said eating spicy foods would lead kids to have sex.
Justin Richardson, author of "Everything You NEVER Wanted Your Kids to Know About Sex (But Were Afraid They'd Ask)," said that was the impetus behind old advertisements that said foods like graham crackers would make kids "wholesome as the great outdoors."
"Mr. Graham and Dr. Kellogg argued that bland foods would prevent kids from thinking about sex and trying it out," Richardson said.
Today we know more, and kids see so much more. Parents are now told talk to your kids more -- Don't wait for them to ask, you bring it up. 20/20 talked with some parents who did.
Alan Davidson decided to talk to his 16-year-old daughter. He told her he was just as embarrassed about what he was going to say as he thought she would be hearing it.
He told her men are "full of it." He warned her, "A man will tell you anything when he has an erection. ... You'll hear things like -- 'but I love you' or 'we don't need to use protection.' "
Davidson said he thought his daughter "looked relieved" after their talk.
She was. Kids 20/20 talked with said they were grateful their parents brought it up.
But couldn't bringing up the subject backfire? If you tell 12-year-old kids about sex, won't they want to go have sex?
"That's the myth and it's a really common fear," Richardson said. "But the research says the answer is no."
Richardson and others say there is no evidence that early talk leads to early sex, and 28 studies of school sex education programs -- regardless of whether they teach abstinence or condoms -- found no suggestion that early discussions about sex lead to earlier experimentation. Nine studies showed it made the kids wait longer to have sex.
Parents may be uncomfortable taking about it, but kids are going to hear about it anyway, Richardson said. "You may not be going there as a parent, but believe me, their friends are going there and the media is going there. They're hearing about sex. What you want to do is lend your voice to the chorus of the talk about sex."
4. Is There Such a Thing as the Seven-Year-Itch?
Just as ancient civilizations believed that their myths were written symbolically in the stars, so is the myth of the Seven-Year Itch.
That myth is symbolized by one of the biggest stars ever -- Marilyn Monroe. It was the title of a movie in which she tempts a man in the seventh year of his marriage toward infidelity.
Is there anything to the belief that spouses are most likely to feel the urge to stray after seven years? Actually, according to evolutionary anthropologist Helen Fisher, it happens a lot sooner, and the reasons for this may go back to the dawn of humanity.
"As it turns out, the standard period of human birth spacing was originally four years. We were built to have our children four years apart and I think that this drive to pair up and stay together at least four years evolved millions of years ago so that a man and a woman would be drawn together and stay together, tolerate each other, at least long enough to rear a single child through infancy," said Fisher, author of "Why We Love."
Following the urge to find a new partner after that four-year period, she says, may have been a way that humans added more variation to the gene pool.
So there is an itch -- it's just a four-year itch, according to Fisher.
"People around the world tend to divorce during and around the fourth year of marriage," she said.
20/20 tried to find out where the myth of seven years came from -- why seven years? One possibility is that it was adapted from an old wives' tale about poison ivy -- that if you ever get poison ivy, the itch will return every seven years. But what Fisher seems to suggest is that humans lack the persistence of poison ivy.
So if the seven-year-itch isn't a total myth, it's just a little mistake in math.
5. Are Women Naturally More Monogamous Than Men?
Dawn Ricci is an expert who knows something about infidelity. She's a private eye who's been in business tailing cheating spouses for 14 years.
"In a three-month period," Ricci said, "there were 211 women who hired our company to follow their husbands. There were 109 men that we were hired by to follow their wives."
If Ricci's business is typical, it looks as if men are cheating twice as much as women. But Ricci said women are catching up quickly.
Evolutionary anthropologist Helen Fisher says she doesn't believe women are naturally more monogamous than men.
"I think we're going to come to find, as women become more economically powerful and express their sexuality more during the course of this century, that women are just as adulterous as men," she said.
Fisher's evidence begins in the bird world.
"Warbler females seem to have a call or a song that they give out when their husband is out of town in order to attract extra mates," she said.
And in most mammalian species, Fisher said, both the male and the female are totally promiscuous
According to Fisher, it's rooted in the Stone Age. "Millions of years ago, if a woman had an extra lover, she would get extra meat from that male. She could get extra protection from that male," she said.
And she could get extra sex as well.
20/20 spoke with a woman, who asked to be identified only as Jennifer, who was happily married for five years, but was until recently seeing another man. She said no one, including her husband, can provide everything -- especially good sex.
"You need one that their touch makes every hair on your body stand on end and just makes your heart race a million miles an hour and you haven't left the bedroom," she said.
And when she would leave her lover after a night of passionate sex, she said she didn't have an empty feeling or wonder when she would see him again.
"Complete opposite. It was like, 'I just had amazing sex, and he's gone, thank God. I have the bed to myself. ' "
Jennifer is human proof that women today may not be more monogamous than men. Since her lover moved away, she's been looking for a new sexual partner through an online dating service for spouses who want to fool around.
That's what keeps Ricci in a business that is growing.
6. Is It Unsafe to Have Sex During Pregnancy?
When it comes to questions about sex during pregnancy, there are as many right and wrong answers as there are pregnant couples. What feels right for one couple may not work for another.
Some say sex during the second trimester is great.
"They say your blood is heavier down there, so I would recommend it for you during pregnancy. It might be better than before," one woman said.
But a dad-to-be sadly disagreed. "The myth for me was that sex would be great during pregnancy. That really didn't happen," he said.
But there is one old wives' tale about sex during pregnancy that ABC News' Dr. Timothy Johnson thought had been debunked for good: the idea that sex during pregnancy could harm the fetus.
It turns out 40 percent do have that fear, according to a poll by BabyCenter.com, the No. 1 Web site for expectant parents.
"I don't know that people are walking around on the streets saying, 'I'm concerned about this,' but when they're in their private moments, and they're faced with the situation in their home, I think they are really concerned," said Linda Murray, BabyCenter.com's executive director.
Some 80 percent of the people who answered the poll thought about the baby in some way when they were having sex.
"Some of them felt like maybe the baby could feel them or see them in some way," Murray said.
And some were very worried about physically hurting the baby, according to Murray.
Dr. Jacques Moritz, chief of gynecology at New York City's St. Luke's-Roosevelt Hospitals, gave us the bottom line about sex during pregnancy.
"There are some medical conditions that might preclude sex. But if your doctor gives you the green light and you feel like it, go ahead," Moritz said.
The biggest surprise in the BabyCenter.com poll: It's dads who say no to pregnancy sex -- 50 percent more than moms.
There's another pregnancy-related myth, that sex at the end of pregnancy can bring on labor. Some 50 percent of the couples in the BabyCenter poll admitted they had tried it. It turns out it may work. Hormones found in semen and hormones released by the uterus may stimulate labor when a woman is ready to deliver. At the very least -- it can't hurt.
"If you're waiting around and you have nothing else to do, you might as well have some fun," said Murray. "You're certainly not going to have sex for the next few weeks."
7. Does Size Matter?
America is a country obsessed with size. From big buildings to big cars to big muscles, Hollywood has shown us that all American males want to measure up -- and that includes measuring up "south of the border," so to speak.
"Men have been assured that size doesn't matter, women have been told that they only have feeling in the first two inches of their vagina," said Joy Davidson, a clinical psychologist and sex therapist.
But according to Davidson, size DOES matter. "We've all been sold a bill of goods about sex and now it's time to tell the truth," she said.
According to Davidson, the notion that size doesn't matter ignores the anatomical facts. "The reason size matters is very simply that women do have nerve endings deep inside the vagina," she said.
Evolutionary anthropologist Helen Fisher agrees, and adds length isn't the only measure that matters.
"When women tell you that size doesn't matter, they're either lying to you or they're lying to themselves. Or they haven't had very much experience. It's one of those three. Because size does matter," Fisher said.
And a woman we spoke with agreed. "Length is a biggie but you gotta have the girth with it, it's the combo really. Got to have it all," she said.
And that's why there's a billion-dollar penile-enlargement industry, selling pills, potions and other products that all say they can make a man larger. But experts say there's no evidence any of these products work.
So it seems men -- and the women they love -- must live with what nature provided them.
8. Do Singles Have a Better Sex Life Than Married People?
Loreen Stevens is livin' the single life. She calls New York City "candyland."
"It's like eye candy everywhere you look. Guys are giving you cards, they're giving you lines," she said.
Shows like "Sex and the City" help perpetuate the conventional wisdom that young and single means lots of fun and lots of good sex, but the 34-year-old Stevens says that's not what she's found.
"I don't want to say it's lonely, but it's so unfulfilling. I'm not comfortable with the casual nature of sex in this city," she said.
J.J. Kandel, another single in the city, has decided that casual sex just isn't satisfying any more.
"It's about finding the right person," said the 24-year-old actor.
Both Kandel and Stevens have stopped prowling and instead are focusing on their careers.
"Emotionally, it's very expensive to put yourself out there and give yourself to people, so let it happen as it will. If I am 70 years old when I find my husband, then so be it," Stevens said.
The movie "Old School" perfectly captures our belief that marriage kills your sex life. Vince Vaughn's character mocks one of his recently married buddies for deciding to have sex with only one person for the rest of his life.
But the real joke is that marriage actually makes sex better.
A University of Chicago study shows that married couples are having more sex -- an average of six times a month, vs. four times a month for singles of the same age. And it's not just more sex, it's better sex.
"Ultimately it's intimate sex that's the most satisfying and fulfilling because the other person already accepts you. They'll accept cellulite or they'll accept potbellies," said clinical psychologist Ellen McGrath.
McGrath says couples who take time to nurture their relationship outside the bedroom will have a better sex life. "They think it's about sex. It's not about sex. It's about the quality of the connection outside the bedroom," she said.
Mark and Dawna Nocera are award-winning professional dancers who teach at their studio in Woburn, Mass. After 15 years of marriage, they say their sex life has never been hotter. They say a great marriage and great sex is very much like a dance. McGrath thinks they've found the secret to great sex and a great marriage.
"Somebody who's just starting out dancing doesn't know anything about the experience that you have 20 years later when you really move," said Mark Nocera. "I think sex is very much like that. It takes a lot of rehearsal to make dancing look that easy."
9. Women Don't Like Porn?
Porn is a man's domain and a turnoff for women, right?
Well, wait a minute. A recent Stanford University study says that contrary to the age-old idea, women do get turned on after watching just a couple of minutes of an erotic video.
Evolutionary anthropologist Helen Fisher says traditionally, erotic videos were made to attract men. They had lots of sex and little if any story line. That was not very appealing to a woman.
Women, according to Fisher, like sexually explicit material if there's some context to it -- porn with a plot.
Companies like Vivid Entertainment and Digital Playground are already banking on it. They claim they're breaking the gender barrier with a softer, more sensual product that's still got plenty of explicit sex.
And with adult movies racking up $11 billion a year -- mostly from men -- women could drive sales up even further.
Director Kelly Holland wants to deliver this passionate porn right into a woman's bedroom through a startup network on Playgirl TV. Holland hopes women will overcome the stigma attached to watching porn and begin enjoying it as an aphrodisiac.
It's all about finding ways to put women in the mood. And with just the right touch, Holland believes she can serve up highly erotic programming to a mainstream female audience that for the most part has been ignored.
"This is the battleground for the feminist movement. And I'm here to bring the battle on," Holland said.
10. Do Herbal Aphrodisiacs Work?
For thousands of years, the secret to better sex has been found along Mother Nature's medicine trail. Chris Kilham, a medicine hunter, treks across the globe in search of plants that add sizzle to sex.
"Every country I travel to has at least one plant that is widely used for sexual enhancement," Kilham said.
Kilham, who teaches plant medicine at the University of Masschusetts-Amherst, reveals his top 10 list of herbal aphrodisiacs in his new book, "Hot Plants." He has now combined these plants into an herbal supplement, also called Hot Plants.
The Food and Drug Administration says there's no proof that herbal aphrodisiacs work.
"Of course the FDA is going to say these don't work," said Kilham. "They have no expertise in herbs. But you have scientists and doctors all around the world who say these things work very well."
ABC's Dr. Tim Johnson talked to doctors familiar with herbs and sexual function to find out if the ingredients in Hot Plants might have an effect on libido.
"Many of these are well-known, well-established in herbal lore. Maca Pura [is] certainly a prosexual; catuaba, certainly a prosexual; rhodiola, definitely a prosexual," said Dr. Steven Lamm.
Recently, a number of studies in reputable journals have looked at some of the individual ingredients in Hot Plants. They were shown to enhance libido and even treat erectile dysfunction.
Labs are one thing -- but what about real life? Can Hot Plants fuel hot sex?
20/20 asked Kathy and Myron Becker to be guinea pigs. Like countless middle-aged couples, their sex life has lost some of its spark.
Kathy was skeptical, but by day three she said she couldn't help but notice a change in her body. "Whatever the herbs are, seem to increase circulation to the pelvic area. And so it gives me the feeling of like, 'Hmmm, I've got a little secret.' "
Her husband certainly noticed. "Kathy seems to enjoy the hum in her nether regions," he said. "I enjoy Kathy's new spark a lot."
But was Kathy Becker's heightened sex drive a physical response to the herbs or a psychological one? That can only be answered by a well-controlled study. Until then, Lamm says it's wrong to simply say herbal aphrodisiacs don't work.
"There are enough active ingredients to have energized this lady," he said. "And it's very possible that it did affect some libido aspect."
That's proof enough for the Beckers, who say, for now, they're a couple of satisfied customers.
[To learn more about herbal aphrodisiacs and herbal medicines, visit the American Botanical Web site at http://www.herbalgram.org.]