I’ve been writing books for more than 20 years and – rather horrifyingly – some of what I’ve written in the first few is no longer true.

Perhaps never.

Today, sex research is a big business. Which means researchers now have the time and money to go back and trace where the original ‘evidence’ to support these claims came from.

In an alarming number of cases, there isn’t any.

Many of the things we believed we knew about sex are unproven. We assume it’s fact simply because we’ve seen or heard it said so many times.

Here’s the latest sex myths to bite the dust.

Tracey Cox debunks six myths, as it’s revealed a lot of the things we thought we knew about sex have no proof to back them up (file image)

No one knows what the average size of a penis is.

Yes. The statistic that’s always trotted out – ‘the average erect penis is five inches long’ – is nothing more than a guess. It’s not even a very good one.

There is no definitive study that proves the average penis size of a man – and it’s highly unlikely there ever will be.

Here’s why: very few men would willingly come forward to have their penises measured by a trained clinician.

Most men are nervous they – literally – won’t measure up.

Nearly all the studies that have been done rely on self-measurement which is notoriously unreliable – and predictably generous.

Men measure from starting points that make it seem larger. The focus is on length and not girth, even though most women agree that girth does impact how it feels.

Never has there been an accurate measurement of the size of men across all cultures and ages by someone who was properly trained.

The latest study – done in Japan – is unlikely to add anything to the mix. Researchers measured flaccid penis lengths rather than erect penises.

Why? One reason was that the men were dead. Researchers measured cadavers.

It takes women less time to get aroused that men.

Tracey (pictured) said there's no evidence to support that peeing after sex reduces the chances of getting a urinary tract infection

Tracey (pictured) said there’s no evidence to support that peeing after sex reduces the chances of getting a urinary tract infection

Most people believe the primary function of ‘foreplay’ is to get women aroused and that men don’t need it at all.

While it’s true that intercourse is more comfortable for women after ‘vaginal tenting’ occurs (the vagina expands to make room for the penis) there is no difference in the time it takes men and women to reach peak arousal.

Thermal imaging was used to measure blood flow to the genitals, which is a reliable indicator of arousal. Researchers asked men and women to view a variety of videos, including erotic. It took both sexes the same time to become sexually stimulated after viewing the video.

There’s also strong evidence that longer foreplay leads to higher levels of satisfaction for men, as well as women, while we’re on the topic.

There’s no point in peeing after sex

Any woman who has ever had an infection of the urinary tract (UTI) was told to go to the bathroom after having sex to decrease the chance of getting another.

The idea was to flush out any bacteria that had been introduced into the urethra by intercourse.

Guess what? There is no evidence to support the claim that this prevents UTIs.

OTHER SEX MYTHS THAT SIMPLY AREN’T TRUE 

If a woman doesn’t have a hymen, she’s not a virgin. Some women aren’t born with one and even if you do have one it doesn’t cover the vaginal opening entirely. Intercourse can cause a tear in the hymen. However, it can easily be stretched to accommodate the penis. It’s elastic and flexible.

Masturbating is bad. Not only is it incredibly good for you – it reduces tension, boosts immunity and eases menstrual cramps – it significantly increases the chances of a woman experiencing orgasm. This is because it helps her develop a ‘road map’ for her body.

Sex can cause a woman to go into labor if she is pregnant. It’s such standard advice some doctors will even tell their patients to give it a try! Actually, it could be the opposite. Having sex can delay labor. US research found women who were sexually active in the final three weeks of their pregnancies carried their babies for 39.9 weeks compared to 39.3 for women who weren’t having sex.

Oysters can make you feel like sex. Oysters look a little like female genitalia but apart from that, there’s no evidence to suggest they are arousing. Oysters contain zinc, which is necessary to produce healthy sperm. However, there are no other magical ingredients that could cause a sexual spark.

Sex affects an athlete’s performance. For years, sports managers and coaches of top sportsmen and women banned sex for fear the athlete’s performance would be weakened. Recent research found – surprise, surprise! – having sex the day before an event has no effect whatsoever on sports performance.

Sex can cause a heart attack.But again, wrong. Regular sex is better for your heart. Men who report having sex two times a week have a lower chance of developing cardiovascular disease that those who have only sex once a year or less.

Both men and women can reach their sexual peak. How do you measure a ‘sexual peak’ anyway? Is it the most orgasms you can have? Is it when you feel your most sexy or best? Although the myth states that men peak at 18, and women peak at 30, this is a myth. There are many ways to experience sexual peaks, depending on how you choose to explore it and who you hook up with.

Every seven seconds, men think about sex. That’s 500 times an hour and more than 8000 times during the 16 hours most men are awake! Alfred Kinsey, a famous sex researcher, is blamed for this one. However, his actual research found that 54% of men think about sex at least once per day, 43% say it several times per week or monthly, and 43% say it more than once per month.

Not quite every seven seconds, eh?

Bizarrely, even reputable medical websites that admit there is no evidence, still say ‘there’s no harm’ in continuing to follow the advice. (Why?)

The risk of developing a UTI in women is still 30x higher than that in men. This is because the urethra is so close to the anus, and bacteria can easily spread. Because our urethras is shorter, bacteria can easily reach the bladder.

The thinking now is that by the time you’re at the peeing stage, the bacteria has already made the short journey.

The vibrator wasn’t invented to make doctor’s jobs easier

There’s a hugely titillating and entertaining story that says vibrators were invented for doctors to use on women to cure ‘hysteria’.

Hysteria was the term that doctors used to describe just about any type of female stress or anxiety related symptoms in the 1880’s. The supposed ‘cure’ for hysteria was for the doctor to masturbate the patient to orgasm. This made appointment times too long and the poor old doctors were tired from repeating this task on so many women. The vibrator is here to make it easier.

Except there’s no literature or data to provide any evidence at all that doctors ever masturbated their patients.

It is true that a Victorian doctor created the ‘vibratode’ but it was originally designed as a medical device for men to treat pain (on non-sexual parts).

In the early 1900s, vibrations were initially intended for general use as household and medical appliances.

Advertisements showed that they could be used by anyone, including babies, children, and adults of all ages to treat everything, from wrinkles to tuberculosis. Savvy women, however, didn’t take long to discover that spectacular things happened when they applied them to their clitoris.

Speaking of which…

The clitoris doesn’t have twice as many nerve endings as the penis

It’s continually reported that the clitoris has 8000 nerve endings in just the tip (the bit you can see).

It’s a ‘fact’ that appears in textbooks and many other highly reputable sources – I’ve written this exact sentence in plenty of my books over the years.

When a sex researcher decided to go back and find the original studies that showed evidence of so many nerve endings, turned out there weren’t any.

All that turned up was a study based on…cows.

There are no studies to tell us how many nerve ends are in the penis or the cerebellum.

There is also no G-spot

Most of you won’t be surprised about this one.

Why is this name still used? Because it’s easier to use that to describe a highly sensitive area inside the vagina than the (more accurate) ‘front anterior wall’ or ‘inner clitoral/urethral stimulation’. (I do a range of sex toys that are called ‘G-spot’ vibrators, simply for that reason – it’s catchier!.

The latest thinking is that the ‘G-spot zone’ is a hot meeting spot for the clitoris, urethral sponge, Skene’s gland and possibly other areas.

Cosmopolitan magazine apologized last Year for using the term and promoted it extensively over many years.

(I edited Cosmopolitan in Australia and can personally vouch for the fact that there was rarely a cover in the 80s that didn’t feature the term.)

It is not anatomically distinct.

Which makes doctors who are currently performing ‘G-spot amplification’ surgery – to enhance a spot that actually doesn’t exist – even more charlatan than they sound.

Listen to Tracey’s weekly podcast, SexTok, wherever you listen to your podcasts. You’ll find info on this, her books and two product ranges at traceycox.com.