We've all grown up hearing all sorts of wives' tales. Some of them seem to make good sense, but a lot turn out to be just nonsense.
We've investigated 10 more commonly held beliefs in our latest myth-busting segment — some that you suggested to us on our "20/20" Web site.
Here's what we found out.
MYTH #10 — A Full Moon Causes Strange Things to Happen E-mail suggestion from Pamela Bartlett of Danvers, Mass.
Lots of people believe that when the moon is full, weird things happen.
Nurses told us their hospital becomes "like a zoo," and police officers told us there are "more lunatics out on the street" during a full moon.
Mitchell Lewis, an astrologer, said, "I warn everybody to be careful around the three days of the full moon."
People pay him for advice like that.
So many people believe the moon changes us, yet Michael Shermer, editor of Skeptic magazine points out that some 36 studies have been conducted on whether there's a full-moon effect. They found nothing.
"No more emergency room visits. No more babies born. No more psychiatric admissions, nothing," Shermer said.
This is embarrassing to me, because in 1984, I reported that a study of murders in Dade County found that more murders were committed during full moons than at any other time.
"Researchers went back, re-analyzed the data, and discovered that there's nothing unusual going on. It's pure chance," Shermer said.
Why do so many of us think weird stuff happens when the moon is full? Because our memory is faulty. We look for patterns, and if we find one, it stays in our brain.
Shermer explained it this way: "We don't remember the unusual things that happen on all the other times, because we're not looking for them. These things go on all the time. And there's no full moon. … We remember the hits, we forget the misses."
MYTH # 9 — You Don’t Gain Weight on Low-Carb Foods?
If you allow yourself to indulge in the hundreds of tempting new products on the supermarket store shelves and forget to count calories, you might be in for a shock.
"The tendency is for the consumer to say, 'oh, it's low-carb. Then it must be low in calories too,'" said Good Housekeeping's nutritionist, Delia Hammock. "That is a myth."
With the same desperation that fed the high-fiber or low-fat crazes, we're now chowing down anything that suggests low-carb, even though that term has never been precisely defined. We're in the midst of a supermarket free-for-all: The label might say "low-carb" or "net-carb" or "effective carb."
"They may be using sugar alcohols instead of regular sugars … They may add more fiber to it … a lot of times they will add soy flour." said Hammock. "They subtract the sugar alcohols, you know, and the fiber and some other things, maybe like glycerols … but your waistline isn't going to subtract those, and people need to understand that."
MYTH #8 — Do Girls Feel More Pressure to Have Sex Than Boys?
It's an image we've all grown up with. The good girl being pressured to go all the way. But contrary to what you may think, nowadays it's boys, not girls, who are feeling the most pressure to have sex, according to a recent study.
We spoke with a group of high school kids from New Jersey, who confirmed the findings of a surprising survey by the Kaiser Family Foundation. It says that 33 percent of teen boys report feeling pressure to have sex compared to only 23 percent of girls. Often it's the boys who put pressure on boys.
Marc, one of the New Jersey teens we spoke with, said guys who are experienced with sex make younger, inexperienced guys feel pressure to do it.
"It gets me nervous," he said, "knowing that I'm at this age and I haven't had it yet, I haven't done it yet. And like everyone else has, so like, maybe — like I feel that I should be doing it," he said.
"I think the majority of the pressure that boys are feeling comes from a kind of cultural expectation. This is what men are like. Men want to have sex, and they'll have sex whenever they can at any point," said Dr. Justin Richardson, a psychiatrist who has written a book about adolescence and sex.
"The pressure comes from society. It gets placed on the shoulders of the boy and the boy in the relationship can then put a little bit of that pressure on the girl," Richardson said.
MYTH #7 — Do Psychics Have Psychic Powers That Solve Crimes?
Lots of people believe that psychics can use special powers to help police solve crimes or find missing people.
Kathy Kupka wanted to believe it. Her younger sister Kristine had been going out with a man Kathy didn't trust, and when Kristine didn't return home after getting in that man's car, Kathy suspected her sister had been killed.
In her desperation to find her sister, she put up a billboard offering a $25,000 reward.
So-called psychics started calling her. And she hired some of them, trying anything she could to find her sister. She even contacted one of America's most famous psychics, Sylvia Browne.
She thought Browne would be the one to help her. "I was super-hopeful. I was like, 'oh that's it. We're definitely going to find her. There's no doubt in my mind.'"
Kupka got on a TV show where Browne was demonstrating her ability to talk to the dead. Browne quickly said Kristine was communicating to Browne, and that Kristine was dead, in New Mexico.
Police checked out Browne's lead, and found nothing.
We wanted to talk to Browne. She agreed, and then backed out. She told us she's solved thousands of cases and never charges grieving families for her services. Several years ago, however, a magazine examined 35 cases Browne had been involved in. They couldn't find proof that she had solved any.
The National Center for Missing and Exploited Children and the FBI also maintain that psychics have never helped solve a single missing person case.
We helped Kathy give it one more try. We asked Kathlyn Rhea, a famous psychic who police work with regularly and credit her with sometimes helping them.
We paid Rhea $1,800 for her services. She explained to Kathy and the private investigator Kathy hired, that Kristine had been murdered.
She was very confident about it, and about where her body was.
She told us to look for: A road that branches off like a Y-shaped divide in the road. What looks like a country church. Something with the letter S. We tried to follow her instructions: But there were lots of Ys in the road; signs with an S.
Rhea wouldn't take us to the spot she was describing.
Mark Klaas , father of 12-year-old Polly, who was abducted and murdered in California, also went to psychics to try to find his daughter. None of them found his daughter's body.
But Kathlyn Rhea later went on a television tabloid program and said she was certain they had the right man because he looked the way she had thought. He was outraged and described psychics as predators who capitalized on families' grief.
Our search for Kathy's sister, following Rhea's instructions, proved fruitless. Rhea says animals must have eaten the body.
MYTH #6 — Does Shaving Cause Hair to Grow Back Faster and Thicker?
No one denies that shaving makes a boy's face feel more manly, and many people believe that's because the more you shave, the thicker the hair grows back. Women seem to think the same thing about shaving their legs.
We spoke to some barbers who think that if you shave, it will make hair grow faster.
But is that really true?
Dr. Howard Sobel, a dermatologist who has spent years studying hair, said this myth is silly. "Think about it," he said. "Little girls grow up and they're told not to shave their hair, because if they start shaving their hair on their legs, they're going to have to continuously shave their hair. And that's not true at all. It's not going to grow back thicker. It's not going to grow back coarser. It's not going to grow back more quickly."
And the little boy who wants to make his facial hair grow is going to be disappointed, Sobel said.
The sad truth, for bald men at least, is, it's all about heredity — it has nothing to do with how often you shave. And while that's good news for women, it hasn't stopped follically challenged men from trying.
MYTH # 5 — If You Carry Your Baby Low During Pregnancy, It's a Boy
It's a nine-month wait to find out the sex of a new baby, leaving a lot of time for guessing. For centuries, predicting the sex of a child has been a popular pastime. Today it remains as much a part of a pregnancy as hand-me-down baby clothes.
ABCNEWS talked with a group of women at a pre-natal exercise class and they were well-acquainted with the theory that if the baby is sitting high in the mother, it's going to be a girl. If it's hanging low, the saying goes, it's a boy.
"These myths are very amusing and perhaps there was some story behind it in the past, but, no, there is no way … by telling whether it's going to be a boy or a girl," said Dr. Paula Randolph, an obstetrician-gynecologist at Columbia University Hospital.
Science does let you find out if you want to know what color to paint the nursery.
Sonograms or ultrasounds are extremely accurate after 18 to 20 weeks. But without an ultrasound, it's little more than an old wives' tale, and guessing.
So, when a woman claims, "I've got this big belly down low, definitely a boy," how does Randolph respond?
"You have a 50 percent chance of being right or wrong," Randolph said.
MYTH #4 — Is It Dangerous to Swim After Eating?
It's the danger in the water your mother warned you about: Swimming right after eating is dangerous and if you do it, you will get a cramp and maybe drown.
Dr. Tim Johnson asked a swimming class what they thought. They believed it. When he told them it was a myth, they didn't believe him.
Dr. Jane Katz has been inducted into the International Swimming Hall of Fame for her contributions as an expert on swimming. But even she can't convince this beginner's swim class at New York City's John Jay College that swimming after eating isn't dangerous.
Katz said, "Part of this myth, … is basically comfort, because after you eat you always get tired. The reason is of course your circulation is going to the intestines and sometimes if you try to exercise vigorously you get a stitch."
But even if you get a stitch, or a cramp, it's not life-threatening.
The American Red Cross agrees. We set up our own experiment with those skeptical swimmers. We had them climb out of the pool and eat a snack. We had them get back in the pool and swim vigorously.
Everybody in class felt fine. One swimmer even said he was hungry.
We tried a tougher test. We asked John Jay's varsity swim team to help. We wanted to see if they could still swim like elite athletes — after eating like couch potatoes.
They all ate a Quarter Pounder and French fries and then swam five laps of sprints.
Even after a heavy, high-fat meal, the swimmers did just fine in the pool.
So the message is: Listen to your body, not your mother. No one recommends you eat a five-course dinner and then swim a marathon. But splashing around or swimming slowly with a full belly is fine.
MYTH # 3 — Are We Destroying Our Forests?
Lots of Americans feel bad when they see images of trees being cut down, because they've been told that America's running out of forestland.
Carl Ross, of the group, Save America's Forests, says we've cut way too much.
"The loss of natural forests in America is a crisis," he said. "And we will lose species forever, and they'll go extinct, if we don't take action now."
Other environmental groups run ads warning of the dire consequences.
But The U.S. Agriculture Department says America has 749 million acres of forestland. In 1920, we had 735 million acres of forest.
We have more forest now. How can that be? One reason is technology that allows us to grow five times more food per acre — so we need less farmland. Lots of what once was farmland has reverted to forest.
But Ross says we don't really have more forests. "We have more areas, in America, with trees on them, that's true. But we have less that are natural," he said.
He's right that many of the oldest trees have been cut down, and about 7 percent of America's forests have been planted by man, but that still means that 93 percent are natural.
Ross is also concerned that loss of old-growth forest is leading to a loss of biodiversity. But while some species have decreased, the populations of many others animals have actually increased in the past 75 years.
Michael Shermer says many people believe America is destroying the forests because environment groups need to scare people to raise money.
"The fear is there," he said, "because, if your goal is to raise funds you have to scare people. You can't tell people things are getting better, and here's the data. You have to tell people things are worse."
The truth, however, is that today in the United States there are two acres of forestland for every single person, and America is growing more forest than it cuts.
MYTH # 2 — Do Expensive Skin Creams Always Work Better?
In the multibillion-dollar skin cream industry, many consumers believe the most expensive product is the most effective.
ABCNEWS examined a few products, with the help of a group of women in their 30s and 40s looking to reduce their wrinkles and age a bit more gracefully.
One volunteer, Christine, was sent to try the most expensive skin cream she could find: Cle de Peau Beaute, La Crème, an anti-aging cream ringing in at $450 per ounce.
Christine was placed on a strict skincare regimen for three months using a gentle cleanser, sunscreen and La Crème every day.
Meanwhile, another volunteer, Kelly, would follow a similar regimen including the prescription cream Avage at one-fifth the price. Avage contains retinoids that are approved by the FDA and clinically proven to change the structure of the skin.
Three months later the women returned to a skincare expert for review and as expected, Kelly had good results. But Christine and the high-priced cream showed no visible improvements. Cle de Peau's manufacturer sent us a statement saying that their products are extensively researched and tested for efficacy before being put on the market, but wouldn't share their research with us, citing trade secrets.
Bottom line: Price is no guarantee and the best wrinkle cream may already be in your medicine cabinet — sunscreen.
MYTH #1 — Are SUVs Safer Than CARS?
More than a quarter of all new cars on the road are Sport Utility Vehicles and part of the reason they're so hot is that a lot of people think ordinary cars aren't as safe in a world populated by SUVs.
In an SUV "You feel safe. You've got this sort of Sherman tank around you," said David Champion, Director of Automobile Testing for Consumer Reports which publishes an annual automobile issue rating car safety.
But that sense of security might be misplaced.
ABCNEWS went with Champion to Consumer Reports' test track in East Haddam, Conn., to see how they determine the vehicles' emergency handling scores. We test drove Chevy's Trailblazer SUV and a Chevy Malibu on three different courses for: handling, skidding, and accident avoidance.
The SUV did very well on the straight road, like a freeway, but when maneuvering quick corners or avoiding potential hazards, the SUV was harder to control. Champion says the better handling Sport Utility Vehicles are the new generation of car-based SUVs.
But many of the most popular SUVs on the road are in some ways glorified trucks, because they are built on a truck chassis.
There are three things that make driving an SUV a little less safe:
• First, they may be harder to maneuver. • Second, SUVs are more likely to roll over, and rollover accidents are particularly deadly. • Third, some people feel safer driving the bigger car, and may lose touch with important cues on the road, such as road slickness.
Industry spokespeople have pointed out that SUVs meet all federal safety standards and have good overall safety records.
But are truck-based SUVs safer than cars? University of Michigan physicist Marc Ross co-authored a report analyzing five years of highway fatality data. The numbers show that while these SUVs can be safer than some smaller cars, like sports cars, drivers are just as safe in a large or midsize car as in truck-based SUVs. Indeed, according to the National Highway Transportation Safety Administration, the vehicles with the best safety records were large four-door sedans, followed by minivans and midsize cars.
While conventional wisdom suggests bigger is better, it's not always true.