Gonay Ogmen is the son of a Christian Armenian family in Istanbul. In December 2010, in the back of his car, he gunned down two young people ? one of them his sister. His reason for committing a double murder: "honour".

Gonay's 26-year-old sister Sonay had fallen in love with Zekeriya Vural, a Muslim Kurd. The couple had tried to convince their families of their love but, finding no support, had secretly got married. They could have run away but they chose to stay, hoping to eventually get their parents' blessing. Less than two weeks later, Gonay called his sister telling her that the family had decided to approve of their marriage and he would like to take them out for dinner to celebrate. It was a lie.

The case grabbed the headlines in Turkey, a country not unused to so-called honour killings and domestic violence against women. The tragedy acquired an unexpected twist when the press found out that Vural's family were, in fact, of Christian Armenian origin and had converted to Islam more than a generation ago.

Last week, after a long trial, Ogmen was sentenced to two life imprisonments, one for each murder. His lawyers tried to have him acquitted of the charge of "honour killing" on the basis that there were no such examples among the Christian community. The case was followed closely by human rights organisations. It also opened up a whole new debate about the role of culture, rather than religion, in the perpetuation of honour-related incidents.

Violence on the basis of "honour" is spreading at a disturbing rate. The problem is not unique to Turkey or the Middle East. It is happening here, too, in the heart of Britain. According to the Iranian and Kurdish Women's Rights Organisation (IKWRO), more than 2,800 honour-related cases were reported in the UK in 2010. Evidence from police forces reporting suggest an increase of 47% since 2009. Attacks are concentrated in London, the West Midlands and West Yorkshire. Women's organisations argue the real numbers could be four times higher because of the stigma of reporting. For some, such as Hanim Goren, who testified against her husband in 2009, it takes decades to break their silence. Her daughter Tulay, a Turkish Kurd, was only 15 when she was murdered in 1999 in Woodford Green, north London, by her father. Her sin was to fall in love with someone who was twice her age and from another branch of Islam.

Apart from the headlines, we know so little about these cases. While writing my latest novel, Honour, I focused on young men such as Gonay ? boys who are taught to believe it is their duty to protect the family honour. I researched cases from Turkey, Germany, Holland, Belgium and Britain, and conversed with Turkish and Kurdish immigrants. I wanted to set the story in London, the multicultural centre of Europe, where there is a relatively better integration, harmony and coexistence than anywhere else today. If it can happen here, it can happen anywhere.

I found it significant that women who are closest to the victims can at times support the decision to kill or remain indifferent to what is taking place, which is tantamount to the same thing. It was also striking to hear a number of mothers say they expected their elder sons to keep an eye on the modesty of their sisters. At the same time, I noticed an enormous pressure on young men and scant tolerance for those who didn't conform. It made me recall Ahmet Yildiz, a Kurdish student who was killed in Istanbul, allegedly by his own father for being openly gay. His story inspired a groundbreaking indie movie called Zenne Dancer.

Both the film and the media coverage helped to increase awareness about the myriad difficulties transgender and gay individuals suffer in patriarchal societies. Any man who does not keep to the ideal definition of masculinity can be ridiculed, bullied or ostracised. The passage from boyhood to manhood is painful and manliness a hard role to play. Without understanding the complexity of the issue and without dealing with the construction of masculinity there is no way we can come close to solving this problem.

Violence against women cuts across all ethnicities, cultures and nationalities of course. Refuge, an organisation that works for women and children fleeing violence, has revealed that, in England and Wales every week, on average two women are murdered by a male who is or was close to them. Gender discrimination seldom materialises in police reports.

Yet there there is something about the concept of "honour crime" that is blurry, if not misleading. For the truth is there is no happiness without freedom and there is no "honour" in murder.

Honour by Elif Shafak is published by Viking, priced £12.99.