There's something we're not talking about. This week, the media machine on both sides of the Atlantic is obsessed with women's bodies, women's sex lives, women's slutty little peccadilloes. Brooke Magnanti, the scientist and former sex worker who became famous for her blog and book Secret Diary of a Call Girl, is releasing a new book which aims to debunk some erotic fantasies about women. In America, Newsweek's cover story by Katie Roiphe asked if feminist liberation makes women more submissive in bed. All of this comes in the context of a cultural "war on women", where rights to abortion, sexual freedom and even birth control are being attacked by people at the forefront of public life. But with all this panting, endless obsession with women's sexuality, why aren't we talking about men?

The changing role of women, in and out of the bedroom, is one of the greatest cultural anxieties of our age. Male sexuality, by contrast, is assumed by most people to be a constant: hard and emotionless, often violent, focused on the conquest of women, on penetration, on dominance. Public money is poured into protecting girls from early "sexualisation", but for boys, sexuality is always assumed to be empowering. "Masculinity" is only ever discussed, as with those pesky inner-city rioters, when it gets "out of control" or is "in crisis", which is usually code for "social unrest" when the polite press doesn't wish to speak about class and poverty.

The first rule of masculinity is that you don't talk about masculinity, much less ask questions about it: it's a bit like Fight Club, but extended to a significant part of the life experience of half the human race. I want to hear men talk about what it means to be one. I suspect I'm not the only one. So, partly out of pure curiosity, and partly in the name of research for a book I'm putting together, I decided to ask some of my internet followers what masculinity, sex and gender meant to them.

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I decided to ask the sort of questions I always want to put to my closest male friends in drunken moments. What were your early sexual experiences? How does pornography affect the way you have sex? Why do you think some men abuse women? Is there really a crisis in masculinity? I drew up the list of questions with a promise to keep all answers anonymous, and asked for volunteers on Twitter.

The response was overwhelming. Where I had hoped for 10 or 20 replies, I received hundreds in the first few hours – from teenagers, pensioners, gay men, straight men, transsexual men, soldiers, students, doctors, fathers, sons. Being drawn from a self-selecting group of men and boys who use Twitter, have the time to fill in a survey and the inclination to trust a strange woman on the internet with their intimate stories, the survey was hardly scientific. The only firm conclusion I can draw is perhaps the most important of all: there are lots of men out there who really want to talk about gender, sex and what it means to be a man, if people would only listen.

My inbox was so flooded with requests for more questions that I quickly had to set up a new email address to deal with them. Many replies opened with expressions of relief – "I've never encountered anyone or anything that was interested in the general ideas men have about masculinity." Others said they had stayed up all night to finish, and some answers ran to many thousands of words.

It's true that men are almost never encouraged to talk about their experience of gender. Women, on the other hand, if we must talk at all, are positively urged to talk about sex and womanhood – and practically nothing else. Indeed, a great many of our most talented writers find themselves relegated solely to writing about "women's issues", filed away in the lifestyle sections as if the first study and expertise of any woman were always her own gender role.

I learned a lot from reading the replies to my survey. Some of my expectations were confounded: a large number of respondents said that they wished that they could define themselves as feminists, but feared being judged for doing so, or appropriating a term that wasn't theirs. Some answers raised other important questions – for example, almost every white respondent skipped the question about how race affected their experience of being a man, except the South African. There were answers that made my heart flutter – "To me, being a man is about outrageously loving my wife" – and others that made me giggle alone in my bedroom, like when one young man confessed that he never feels more masculine than when he's asked to remove a difficult lid. As a feminist, as well as a person with small hands who eats a lot of marmalade, I can confirm that it is indeed useful to have men around to get the lids off things, although not just for that reason.

Some of the answers were riddled with fear of being judged. Many respondents were worried about defining themselves as feminist – "It almost feels like I'm hijacking the term from them," said one 27-year-old. "But if asked I will always say yes, I am a feminist." "Patriarchy controls male behaviour in similar ways," wrote another young man. "Society pushes men to live up a construct of alpha male behaviour: being sexually aggressive, emotionally detached, competitive with each other."

Some respondents spoke of their fear of overstepping the bounds of consent during sex, or of threatening women; and many had violent contempt for "the section of men across the globe", as one American in his thirties put it, "that are f*cking it up for the rest of us". He continued: "I'm tired of the sexist legislation, I'm tired of the rape, I'm tired of the genital mutilation. What is wrong with these guys and how can I slaughter them like the animals they are?"

Real men, we are told, don't question masculinity. Even to raise the issue would be to admit uncertainty, and uncertainty is for women. The first thing little boys learn at school is that there's nothing in the world worse than being "like a girl", with the possible exception of being "gay". So men keep quiet. If they happen to cry easily, if they happen to be uninterested in competition, sports or drinking, if they are physically timid, if they don't feel ready for sex, if they aren't aroused by digitally enhanced, soft-porn women, or submissive women, or women, the last thing they're supposed to do is talk about it. That might give the game away. It might reveal that male power is fallible, and vulnerable, and nothing but human. The time has come to give the game away. The time has come to have an honest talk about masculinity.