Shaun R Harper: Many men talk like Donald Trump in private. And only other men can stop them.

Republican presidential candidate Donald Trump. Photo / AP

I know Donald Trump. Though we have never met, I know him well, writes Shaun R Harper, executive director of the Center for the Study of Race and Equity in Education.

At several moments throughout the campaign, I have felt that something about Trump was disturbingly familiar, but I couldn't quite pinpoint it. After seeing the video of this presidential candidate and married man talking about kissing women, grabbing their vaginas and using his celebrity to get them to do whatever he wants, I now fully recognise the guy I have known since I was a teenage boy. The Trump on that video is a sexist, misogynistic, womanising cheater who degrades and sometimes sexually assaults women. I know this man and so many like him. I wish I didn't, yet I do, and I have for a long time.

Truth is, many men objectify women and say outrageously offensive things about their breasts, butts and other body parts in spaces we occupy with each other. In his response to the video's release, Trump explained that his comments were "locker room banter." His is a "boys will be boys" defense of sexism and the objectification of women, but he wasn't incorrect that some men do, indeed, talk that way. And such talk is not confined to gyms and country club showers, but occurs too often in other spaces where men are among other men - in fraternity houses, on golf courses, in barbershops, at bars. I have even seen men stand aside and engage in this kind of talk about moms at kids' birthday parties. Unfortunately, the kinds of words we heard from Trump are commonly spoken when men are with other men. Those who participate in this "banter" are rewarded. Those who choose not to engage, and especially guys who critique such statements, have their masculinities questioned and risk being placed on the outskirts of social acceptance.

I have spent much of my career studying men and their masculinities. My research has put me in conversation with thousands of young men, mostly high school and college students. Many have told me that they learned to be Trumps in middle school, sometimes earlier. Media, parents, family members and peers shape how boys are taught to think and talk about women from a young age. While I am quite older than they are, I still understand and relate to what my research participants tell me. The horrifying things Trump said in that video are comments I've heard from male friends of mine since I was a teenager. As a young boy, I witnessed older men appraise women's bodies and heard them say what they would do sexually (for example, "Look at the ass on that one" and "I would bang her all night long"). Truth is, I have known Trumps most of my life.

Despite their familiarity, the words I heard Trump speak in that video horrified me. Most disturbing was this: "You know, I'm automatically attracted to beautiful - I just start kissing them. It's like a magnet. Just kiss. I don't even wait. And when you're a star, they let you do it. You can do anything. Grab them by the p***y."

Kissing or groping someone without consent is sexual assault. It's popular for men to brag about similar behaviours. Young men I have interviewed say their male buddies often affirm and applaud such statements. Rarely does one man hold another accountable or raise his consciousness about the vile acts he's describing. Details of sexual conquests - even unsuccessful attempts like Trump taking a married woman furniture shopping in hopes of having sex with her - are typically celebrated. And because bragging of this kind is common, men in my research confess that they don't always recognise that they and their peers talk about women in deplorable ways. Hiding it behind the guise of "banter" or jokes only makes the problem worse by making it seemingly acceptable. It is unacceptable.

When men fail to challenge other men on troubling things they say about and do to women, we contribute to cultures that excuse sexual harassment, assault and other forms of gender violence. I know from my research that confronting male peers is difficult for a 14-year-old high school student-athlete who desperately wants his teammates to like and accept him. He needs his coach to step up and disrupt locker room banter. Perhaps Trump, who was 59 when the video was recorded, and Billy Bush, whose comments were also awful, never had a coach or anyone else confront their sexism. College men need opportunities in their classes and elsewhere on campus to see women differently, develop more progressive perspectives about women's roles and worth in our society and undo ways they have been socialised to view and talk about women. Young men - not just those who spend time in locker rooms - need their dads, uncles, male teachers, ministers, rabbis and other adult men in their lives to teach them how to appreciate and talk about women.

But too many adult men fall short of this ourselves, especially when we are in "men's only" spaces with guys whom we need to affirm our masculinities.

I am fairly certain that hearing the vulgar words Trump spoke over a decade ago will compel many more women to vote against him next month. Electing the first female president will not end sexism, though, any more than electing Barack Obama ended racism. To make progress, men need to do more than vote against Trump. We must stand up to him and call out others who say things similar to what we heard him say on the video. We have to stop excusing the disgusting degradation of girls and women as "locker room banter." Feminists and courageous others have done much to contest exchanges like the one between Trump and Bush. But it takes men like me to hold our friends accountable for things they say and do to objectify women. We must challenge their values, language and actions.

I have known Trumps far too long - they are my friends, my fraternity brothers and so many other men with whom I routinely interact. I understand now, more than ever before, that letting them talk this way about women makes me just as sexist. By excusing their words and actions, I share some responsibility for rape, marital infidelity and other awful things that men do. I want other men to recognise this, too - not only because they have mothers, wives, sisters, aunts or daughters - but because sexism hurts all women and men in our society.