Similarly, less than 40 per cent of women who had had sex with other females since the age of 18 said they considered themselves lesbian or bisexual, the US National Health and Social Life Survey found after interviews with a representative sample of 150 million Americans.
Details of the survey were released by Stuart Michaels, a researcher at the University of Chicago who helped manage the survey. He said the generally held opinion that sexuality was easily classified did not stand up to analysis.
"Somehow in our society we have come to think that homosexuality is a singular and simple phenomenon that can be summarised as a single number.
"The debates have assumed we have something that is absolutely clear when we talk about homosexuality in that all people can be divided into two or at most three camps, as homosexual, heterosexual or bisexual. The survey disputes that notion," Dr Michaels said.
"It's a much more complicated phenomenon. About 10 per cent of the men and 9 per cent of the women in the survey report some element of homosexuality in their adult lives. That's either behaviour, sexual feeling towards people of the same sex or a self-definition of being homosexual.
"Under 50 per cent of the men and women who've had a homosexual experience since the age of 18 define themselves as homosexual or bisexual.
"That's about 5 per cent of the population who have had a homosexual experience since they were 18. Less than half of these people, however, define themselves as gay, lesbian or bisexual."
The survey found no evidence that homosexuals were likely to be significantly more promiscuous than heterosexuals.Reuse content