A Dutch study has found that men who suffer from premature ejaculation may be able to blame their genes.
A study of nearly 200 men in the country found those who climaxed too soon during intercourse had a version of a gene that controls the hormone serotonin. Men with this version ejaculated twice as quickly as other men in the study.
The Utrecht University researchers say they believe serotonin levels are what control the rapidity of ejaculation.
The volunteers in the included 89 men who had always suffered from the problem from their first sexual contact onwards. For a month, their female partners were asked to use a stopwatch at home to measure the time until ejaculation each time they had intercourse. A funny picture, yes, but that's what they did.
The results were compared with then compared with 92 men with no history of such problems. In the men with premature ejaculation, serotonin appeared to be less active between the nerves in the section of the brain that controls ejaculation.
"This contradicts the idea, which has been common for years, that the primary form of premature ejaculation is a psychological disorder," says Dr Waldinger.
However, sexual psychotherapist Paula Hall, says while that may be true: "Premature ejaculation is definitely not purely psychological. But there can be a psychological element. The acid test is how much control they have on their own. If the problem only occurs with their partner then it is more likely to be psychological."
But she agrees that there is good evidence that serotonin is linked ejaculation and researchers are developing drugs to prolong the hormone's action. Around a third of men are believed to suffer from the problem.