February 2, 2025 - 4:00pm

What are we to make of new survey results showing that the number of young people in the UK who identify as lesbian, gay, or bisexual (LGB) tripled between 2014 and 2023? Currently, more than a tenth of Britons aged 16-24 identify as LGB, while almost 10% of young women identify as bisexual.

One conclusion which should not be drawn here is that these findings represent actual changes in sexual feelings. Fundamental psychological traits are unlikely to shift in less than one generation. However, the words we use to describe ourselves — and even how we think about ourselves — can change rapidly. And young people, especially young women, may be especially susceptible.

Large surveys conducted in North America before 2014 showed that a large majority of people identified as “completely heterosexual”, but that a significant minority rated themselves as “mostly heterosexual”. The most common non-heterosexual identity was “mostly heterosexual”, which included around 10% of women and 4% of men.

In contrast, only 0.6% of women and 1.4% of men in these older studies identified as bisexual, which was explained to respondents as an equal attraction to men and women. The new UK survey only asked how respondents identified their sexual orientation, without providing any guidance as to how they should understand “bisexuality”. There was no “mostly heterosexual” choice. It would therefore not be surprising if a number of people with “mostly heterosexual” feelings identified as “bisexual” in the UK survey. Consistent with this possibility, research from elsewhere finds that LGB identification is about twice as common as actually engaging in same-sex sexual behaviour.

This presents a couple of questions. Firstly, why are women especially likely to identify as bisexual?  Secondly, why has their rate of bisexual identification increased in the UK in such a short time?

Women’s higher rate of bisexual identification may reflect a fundamental sex difference in the expression of sexual orientation that I have studied in my laboratory. In our studies, we recruit heterosexual and homosexual adults of both sexes. We show them audiovisual pornography featuring either male actors or female actors but not both. We measure both their subjective response, by asking them how aroused they are, and their physiological arousal, measuring their genital response. Men’s subjective and genital response patterns match their sexual orientations. Gay men get much more aroused by male videos, and heterosexual men get more aroused by female videos. Men with bisexual arousal patterns exist, but are less common than even gay men.

Women show a different pattern. Lesbians like the female videos much more, but their genital response is only slightly higher to the female stimuli than to the male stimuli. And heterosexual women show no preference — subjective or genital — for either male or female videos. Their arousal patterns might be described as bisexual, or at least indifferent. Heterosexual women, unlike most men, are unburdened by an arousal pattern that directs them towards one sex or the other. Without this constraint, bisexual identification may be easier for them.

Another reason why men are less likely than women to identify as bisexual may be the consequences for their respective desirability. Women tend not to like bisexual men, romantically at least. Conversely, men tend to be fine with bisexual women.

But why has it become more common for women to call themselves bisexual? Other research suggests that bisexual identification is concentrated among politically liberal young women. Progressives have recently been especially fond of embracing identity politics and marginalised groups, and rejecting traditional norms. To some, bisexual identity could be a badge promoting these ideas.

Women are also susceptible to certain kinds of social influences. When harmful, such as rapid-onset gender dysphoria, these might be called “socially contagious epidemics”. I don’t see bisexual identification as destructive, but its increase may reflect a similar dynamic.

Will these changes persist, or even grow? Really, it seems likely that they will recede, representing more a meme than a movement. But if 20% of young British women are bisexual in 2033, I’ll be glad to admit my error.


J. Michael Bailey is a Professor of Psychology at Northwestern University