National sex survey: One in 10 women in UK forced to have sex against their will In an alarming set of figures which researchers say could show sexual coercion becoming "normalised," around 40 per cent of incidents were at the hands of a current or former partner, while the average age of a female victim was 18. The statistics come from the National Survey of Sexual Attitudes and Lifestyles (Natsal), a study conducted once every decade and which questioned 15,000 people aged 16 to 74. By comparison, when asked "since the age of 13, has anyone made you have sex with them, against your will?," only one in 71 men said they had. Wendy Macdowall, the lead Natsal author, said the issue of what the report calls "non-volitional sex" needs to be addressed at a much earlier age. Macdowall said sexual coercion had become "normalised... with rape at the extreme end of the spectrum," according to reports in the Guardian. She said there was a need for early intervention in schools to deal with the problem "before those gender stereotypes are developing" and because "somebody who has been victimised at a young age is much more likely to be victimised later." The study, published in the Lancet today, shows that for both men and women the person responsible for coercing them into sex was much more likely to be known to them, accounting for around 83 per cent of incidents. The survey asked questions covering a broad range of topics relating to sex in modern Britain. It showed that women are having sex younger and having more partners than ever before - and that those partners are not necessarily going to be men. And it also found that couples are having less sex than at any point in the past two decades, with researchers saying the drop in libido could be down to the distractions of modern life, social media and money worries.