Half of British young people say they are not 100 per cent heterosexual, according to a new survey.

When asked to plot themselves on a scale of sexuality, ranging from exclusively heterosexual to exclusively gay, 72 per cent of adults and 49 per cent of people aged 18 to 24 chose a position other than completely straight.

The survey, released today by respected pollsters YouGov, found only four per cent of adults class themselves as completely gay, with just under a fifth putting themselves somewhere in between the two extremes.

With each generation, people appear to see their sexuality as less set in stone.

Of 1,632 people surveyed, 60 per cent of heterosexuals and 73 per cent of homosexuals supported the idea that sexuality is a scale.

The world saw an outpouring of emotion after the Supreme Court made same-sex marriage legal across the US earlier this year ( Getty )

Less than half of 18-to-24-year-olds think they are completely straight and 43 per cent say they are somewhere in the middle, allowing for a few respondents who had no opinion.

This compares to those aged 60 and over, where 89 per cent said they were completely straight or completely homosexual.

Most of these respondents would have been of school age when male homosexuality was legalised, in 1967.

About a quarter of those aged between 18 and 39 said reported having had a homosexual experience, compared to just nine per cent of those aged 60 and over.

More men report having had a gay experience. A fifth of males, compared to 14 per cent of females, report having had a sexual experience with someone of the same sex.

Respondents were asked to put themselves in one of seven levels of sexuality, ranging from 0 (100 per cent heterosexual) to 6 (100 per cent homosexual). Levels one to 5 were increasing levels of homosexuality.

Will Dahlgreen, a data journalist at YouGov, said: “Clearly, these figures are not measures of active bisexuality - overall, 89 per cent of the population describes themselves as heterosexual - but putting yourself at level one allows for the possibility of homosexual feelings and experiences.

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“More than anything, it indicates an increasingly open minded approach to sexuality.”

A Gay Pride march in Uganda, which attempted to outlaw homosexuality just last year, earlier this month ( Getty )

The world saw an outpouring of emotion after the Supreme Court made same-sex marriage legal across the US earlier this year.