Anal sex between young men and women often seems coercive and painful, suggests research published in the online journal BMJ Open.
Feedback from young people reveals an oppressive culture around anal sex, with some young men apparently neglecting or not caring about young women's consent or pleasure - both when they have anal sex and when they talk about it with their friends.
More open discussion is needed to challenge the culture and attitudes surrounding anal sex between young men and women - a subject that people often find difficult to talk about in many social contexts, say the researchers.
They interviewed 130 16-18 year olds from diverse social and economic backgrounds living in different parts of the country: London; an industrial city in the north; and a rural area in the south west.
The interviews explored the range and meaning of different sexual practices, and included nine group and 71 individual in-depth discussions in 2010, and further interviews of 43 of the in-depth interviewees in 2011.
The group discussions focused on what sexual practices participants had heard of, what they felt about them, and whether they thought their peers would engage in them - and if so, under what circumstances.
During the in-depth discussions, interviewees were also asked what sexual practices they had engaged in, under what circumstances, and how they felt about them. Young people described‚ a culture where men compete to have anal sex with women, even if they expect women to find it painful.
Women also said their male partners repeatedly asked them for anal sex. And their accounts suggest that they had sometimes ended up having anal sex without giving their explicit consent. "Currently, this apparently oppressive context, and indeed the practice of anal heterosex itself, appears to be largely ignored in policy and in sex education for this young age group," write the researchers.
The interviewees sometimes said that young men wanting to copy what they saw in porn, explained why they had anal sex, but the feedback suggests that other factors are more important, say the researchers.
These include a lack of concern about getting consent, or the levels of pain female partners might experience, and competitiveness among young men to have anal sex with women. 'People must like it if they do it' was also given as an explanation by those who hadn't experienced anal sex, which, the researchers point out, was made alongside the seemingly contradictory expectation that women would find it painful.
Not all men coerce their partners, the researchers emphasise. Some young women may wish to have anal sex, and both partners may find it pleasurable, they add.
But the findings suggest that teachers, parents, and wider society need to talk more openly about anal sex with young people, particularly the importance of "mutuality" - where both partners listen and respond to each others' desires and concerns, they write.
Attitudes, such as the inevitability of pain for women, or the failure to recognise or reflect on potentially coercive behaviour, seem to go unchallenged, which risks coercion emerging as a dominant element of anal sex, they add.