I had sex with my brother but I don't feel guilty

Strangely enough, Daniel's wedding day didn't upset me at all. It was his 30th birthday six months later which really got to me, as he stood there with his wife Alison while they greeted the guests. I can honestly say that that was the only time when I felt real envy and wished desperately that it was me standing beside him, arms round each other as we showed the world how much we loved each other.

It's not as if I'm not allowed to love Daniel, but the way we feel about each other isn't something that we can share easily with anyone else. Daniel is my brother, but since I was 14 we've had a sexual relationship - and that's not something that many people would feel comfortable with.

I've only ever spoken about this once before, and even then it was very much in the abstract. While I was still at university a friend had a major misunderstanding with a relatively new boyfriend when one of his friends had reported back to him that he'd seen her hugging and kissing another man in the union bar. She was firstly annoyed at being questioned and became even more exasperated when she explained that the man in question was her brother, as her boyfriend refused to believe her. Their loud discussion took place in the union with an interested audience, until he finally stamped out in fury, still refusing to believe her. As she flounced back to join us she made a remark about preferring her brother to any other man, whereupon one of the crowd said “Yuck, how pervy!” As she sat down beside me she muttered something like “It's not that strange,” and three or four drinks later I quietly asked her what she'd meant.

In a survey of 796 undergraduates at six New England colleges and universities, 15% of the females and 10% of the males reported some type of sexual experience involving a sibling. Fondling and touching of the genitals were the most common activities in all age categories. One-fourth of the experiences could be described as exploitative either because force was used or because there was a large age disparity between the partners. Reactions to the experiences were equally divided among those who considered them positive and those who considered them negative. Females were more likely than males to have been exploited and feel badly about it. Few participants of either sex ever told anyone. The research finds evidence that such experience may have long-term effects on sexual development. Females who report sibling sexual experiences, both positive and negative, have substantially higher levels of current sexual activity. Their level of sexual self-esteem may also have been affected, but more selectively. Those with positive sibling experiences after age 9 have more sexual self-esteem. However, experiences with much older siblings taking place before age 9 are associated with generally lower levels of self-esteem and no increase in current sexual activity.

Reunions between birth relatives separated by adoption can spark off intense sexual feelings, according to a visiting psychiatrist.  Maurice Greenburg, a consultant to London's Post-Adoption Centre, was speaking at the Adopting New Ways conference about genetic sexual attraction, a phenomenon he has studied.  During the study he analysed 40 case histories and interviewed 10 people who said they had experienced this attraction.  The reunions included those between parents and children and between siblings.  The people concerned were both heterosexuals and homosexuals.

Can sex between close relatives ever be acceptable? Johann Hari on the queasy issue of 'consensual' incest.