The four 7 July bombers may have been driven by a desire for self-destruction rather than political or religious motives, a psychologist claims.
Three bombs were detonated on the London Underground
The bombers may have felt like failures and were psychologically vulnerable, Professor David Cantor says.
The director of Liverpool University's Centre for Investigative Psychology made the claims at a London conference.
Prof Canter said that suicide bombing was present in many cultures and should not be exclusively linked with Islam.
Four suicide bombs were detonated on three tubes and a bus in central London on 7 July, killing 52 commuters and injuring about 700.
Prof Canter said: "We can't blame religion for these individuals' ways of seeing the world."
"We are looking in Britain to a very small and unusual group of individuals who begin to see themselves as separated off from other groups, and who possibly see themselves as having given in to weaknesses and having failed in various ways.
"And the only way they can deal with that is by an act which is in its own way heroic but will also make a statement about what it is they are undertaking and what it is they are trying to achieve."
Limited evidence on the psychology of suicide bombers around the world showed they tended to have a simple "us and them" mentality, he told the delegates.
The key to tackling the causes of suicide bombings was possibly to make them see the broader picture, Prof Canter said.
He added: "We have to break through the 'us and them' mentality and make people see that they are part of a much more complex and rich mixture of society."
"There are many other ways of having an influence than killing oneself."