8 'facts' you learned about sex growing up that aren't actually true

Perhaps this "fact" is a way to scare teens away from sex or at least into having protected sex, but fertility varies from person to person and unprotected sex doesn't always result in a pregnancy.

A woman can only get pregnant when she's ovulating, something that only happens once a month. The process involves a mature egg dropping into the ovaries; if sperm fertilize that egg within 12 to 24 hours of this drop, it results in pregnancy.

But even having unprotected sex during this time only leads to a 20% chance of getting pregnant, Dr. Maureen Whelihan, an OB/GYN at the Center for Sexual Health and Education told Self.

Additionally, a woman's fertility starts to decline in her late 20s, so the likelihood of getting pregnant begins to decrease even with unprotected sex as she gets older.

Deyjah Harris, daughter of the rapper T.I., recently spoke about feeling "overwhelmed" after her father revealed he takes her to the gynecologist every year to check her hymen is still intact.

The ritual appointment was, in theory, for him to check that Deyjah was still a virgin, and once he shared this fact it swept the world.

However, hype aside, the idea of an intact hymen being a sign of virginity is flawed.

The hymen, a membrane at the opening of the vagina, is not the same in all bodies. Some are broader, some cover more of the opening than it does others. In general, it does not cover the entire opening.

There's a theory that women who spend a ton of time around each other, like roommates, coworkers, or best friends, will eventually have their menstrual cycles sync up so they occur at the same time. Science, however, has never supported this claim.

For one, researchers haven't found any mechanism in women's bodies that would allow this sync-up to occur, gynecologist Dr. Jen Gunter previously wrote for the New York Times.

Plus, a period tracking app that used its user data to determine whether there was any link between women's period schedules and the time they spent with other women found no link.

It's most likely that when a friend or colleague has their period at the same time as you, it can be explained by an overlap, since women's cycles can vary in length. There's also the issue of recall bias, where women tend to remember instances where the sync-up theory applies rather than instances of other women they're around whose periods don't sync up with theirs.

The concept of the G-spot, a supposed pleasure-inducing zone inside the front wall of the vagina, has been a popular topic in women's magazines for years. But it's remained elusive for women themselves, likely because the G-spot doesn't exist.

"It is not surprising to me when I hear of women who fake orgasms with male partners," Gunter wrote in her book "The Vagina Bible." "After all, they have been led to believe that a female orgasm should be reached with a penis by way of a imaginary spot."

Researchers who have more recently studied this concept have been unable to locate this special spot that was supposedly found in 1950 by German researcher Ernst Gräfenberg.

Gunter said it's likely that Gräfenberg misconstrued other parts of a woman's genitals, like the nerve ending-packed clitoris, as this seemingly new discovery of the G-spot.

"The lower part of the vagina, close to the urethra, will feel great for many women because stimulation here is accessing the clitoris, but it takes the right stimulation — it is not an 'on/off switch,'" Gunter wrote.

Read more: The doctor behind 'The Vagina Bible' takes 5 precautions before waxing her pubic hair to prevent ingrown hairs and infection

Sex ed classes of previous decades often used scare-type tactics when it came to STD prevention.

In one Insider employee's 8th grade sex ed class in an Atlanta suburb, "they had us make a graveyard in the hallway where we made and decorated headstones for people who had died from STDs," the employee said. "They also made us watch a video that was just photos of diseased genitalia."

One Twitter user said that during his freshman year of high school his class had to look at a slideshow "of folks infected with various STDs, like, closeup of green oozing genitals."

It's teachings like these that stigmatize people with STDs like chlamydia, syphilis, gonorrhea, and HIV. These STDs can be cured or treated with medication to help prevent a person with an STD from spreading it to sexual partners.

Additionally, people can lower their risk of spreading STDs to partners if they use condoms.

Regular STD testing can also help prevent the spread of these infections without compromising a person's sex life.

In 1981, the U.S. government began funding abstinence-based sex ed under the Adolescent Family Life Act, under which schools can still promote abstinence as the only way to prevent pregnancy and STDs so long as they don't directly reference any religion.

Sure, abstaining from sex completely is the only 100% effective way to prevent pregnancy, but for most people, this contraceptive method isn't realistic.

Other forms of birth control, including the pill, IUDs, condoms, and implants are all highly effective at preventing pregnancy too and allow people to enjoy sex.

The birth control implant, for example, is 99.9% effective at preventing pregnancy and pills are between 92% and 97% effective, according to the American Sexual Health Association.

Read more: 7 things you should know before you decide to stop using birth control

People who were taught abstinence-only sex ed may have been taught that having sex before getting married or having sex with more than one partner is unhealthy even though no science fully supports this idea.

It's true that having more sexual partners could increase a person's chance of getting an STD, but there are ways to prevent STDs or cure them.

The idea that sex out of marriage or sex with more than one partner makes a person dirty is rooted not in science, but in the religion-based concept of purity, according to clinical psychologist David J. Ley.

"The purity movement infused sexual education with a notion that our sexual urges are immoral, and that we are better people when we choose to live above them," Ley wrote for Psychology Today. In reality, sexual purity is a construct, not a fact based on the number of partners a person has had.

One female Twitter user said she was taught "women release a bonding hormone during sex that men don't release that makes us catch feelings every time there's a penis in the vicinity so definitely we shouldn't have sex before marriage or we'll end up so sad we'll have to turn to secularism & drugs about it."

Although it's true women release happy-making hormones like dopamine and oxytocin during sex, the same is true of men. That's because these hormones come from the brain, not the genitals.

• Read more:
• How my life changed when I stopped wasting time on terrible sex
• The awkward, technical truth behind Hollywood sex scenes
• 17 times celebrities got brutally honest about sex