Teenagers face far less homophobia among their peers than ever before because the stigma of being gay is melting away in secondary schools, according to a new book.

The anti-gay prejudices of the 80s and early 90s are disappearing, claims Mark McCormack, a sociologist at Brunel University. McCormack spent six months in each of three schools in the same UK town to study attitudes of 16- to 18-year-olds. In his book, The Declining Significance of Homophobia: How Teenage Boys are Redefining Masculinity and Heterosexuality, he says that, for this age group, pro-gay attitudes are held in high esteem and homophobia is as unacceptable as racism. He also suggests that the phrase "so gay", used to rubbish things, is unrecognisable to teens as homophobic.

"A lot of prejudice is based on stigma," he added, "and actually the stigma around being gay has dropped off. The coming-out narrative is changing too, with parents being OK." The internet had helped to dispel the isolation young gay people have felt in the past, he said.

"Twenty years ago, there were few openly gay people in the media; today, you can turn on Radio 2 and there's Graham Norton, Alan Carr, Paul O'Grady, all of whom now are mainstream. There is a fundamental change in the cultural discourse.

"An LGBT [lesbian, gay, bisexual or transgender] character in Coronation Street is a major thing then suddenly its forgotten then they're just a central character. It's much more accepted that there are happy gay people out there, not tortured by homophobia and prejudice."

McCormack found teenagers to be open about their sexuality. "It's had a huge impact on the LGBT kids: they are happy, out and proud at school. That's better for gay kids and better for straight kids too."

But he says the change in attitude may well be peculiar to this age group: "I'm not saying the battle is over against homophobia, but it's getting better.

"These young people see homophobia as wrong. Guys used to prove they were straight by being homophobic. Now, when young guys want to show they're straight, they do it in a more positive way by joking about being gay."

McCormack's findings do not ring true with everyone. "It's definitely not our experience, I'm afraid," said Jess Wood of youth support charity Allsorts. Its 2010 survey of Brighton schools found that 16% of bullied children in primary and 23% in secondary schools reported that the bullying was homophobic in nature. Half of lesbian, bisexual, gay or transgender teens reported homophobic bullying at school or college.

"It remains the second-highest reason children give for bullying," said Allsorts' director, Jess Wood. "I do think to try and eradicate the word 'gay' is a waste of time; it's embedded in the language, but it's a bogus argument to suggest it's anything other than hideous for gay people to hear the negative associations of the word."

Ruth Hunt of Stonewall UK also urged caution. "I think it matches what we know in that some schools which are good on this are very, very good. But plenty are not. Although we are seeing shifts in the way schools think about how boys should be seen to behave, we still see many schools with significant problems. We still have schools who tell us they have no gay pupils.

"As for the abuse of the word 'gay', it's dangerous to be dismissive by using the argument, 'Oh the kids think it's fine and so it's fine'. That doesn't stand up. If the word is being used to mean stupid, then how does it make a young gay person feel? It makes them feel stupid. It's an inevitable connection in their minds."