Edinburgh University researcher, Jamie Heckert, wants to find out about sexual orientation. He isn't interested in gay genes, though. 'I want to talk to people about their experiences,' says Heckert.

Heckert is currently recruiting participants for his ongoing research project. He wants to talk with people in relationships with someone who has a different sexual orientation than they do. 'Many people consider themselves gay, bisexual or straight. I'm interested in these, as well as other "sexual orientations" like bi-curious, mostly straight, questioning, confused, variable, fag hag, etc. I am also looking for people whose sexuality has changed.'

So far, he has talked to: a woman who used to consider herself bi, but now thinks of herself as straight; a straight identified man who fancies androgynous women; and several bisexual or queer women. He has also been in contact with a man who identifies as straight, with only one exception. He is, of course, also looking to talk to people who consider themselves simply lesbian, gay or straight.

'Basically, I want to talk with a wide variety of people about how well they fit into sexual orientation categories. How do they feel about labels? What sort of pressures have they experienced?'

But why mixed relationships? 'Well, partly because no one else has done it. But mostly because I think having a partner with a different sexual orientation makes you think about these things a bit differently. Also, I can't just go up to random people on the street and ask them about their sexualities!'

Heckert is preparing for a bit of a research road trip around Scotland and England this autumn, stopping off to do interviews wherever he can find people in "mixed relationships".