The percentage of Americans who have had sex with the same gender has doubled in a quarter of a century, according to a new study.
Researchers found 8.7 per cent of women had had sex with at least one woman in 2014, up from 3.6 per cent in 1990. There was a similar rise among men from 4.5 per cent in 1990 to 8.2 per cent in 2014.
Among Millennials -- adults aged between the ages of 18 and 29 during the 2010s -- 7.5 per cent of men and 12.2 per cent of women reported having had a same-sex experience.
Lesbian sexual experiences were more likely to occur when women are young, but the same was not true for men, the researchers found.
Professor Jean Twenge, a psychologist at San Diego State University who worked on the study, said: "These large shifts in both attitudes and behaviour occurred over just 25 years, suggesting rapid cultural change.
"These trends are another piece of evidence that American culture has become more individualistic and more focused on the self and on equality.
"Without the strict social rules common in the past, Americans now feel more free to have sexual experiences they desire."
The figures come from the US General Social Survey, which includes information about more than 30,000 adults.
This has asked Americans about their attitudes toward same-sex sexual behaviour since 1973 and about sexual partners since 1989.
Between 1973 and 1990, the percentage of adults who believed "sexual relations between two adults of the same sex [was] not wrong at all" rose by just two points from 11 to 13 per cent.
But in the last 25 years, the figure has risen to almost half of all adults and 63 per cent of Millennials.
The researchers published their findings in the journal Archives of Sexual Behaviour.
