The number of young teenagers identifying as lesbian, gay or bisexual has sharply declined in recent years, according to new data from the Center for Disease Control and Prevention (CDC).

Interpreted by San Diego State University psychology professor Jean Twenge, the data shows the number of ninth graders in the US (those aged 14 and 15 years old) identifying as LGB fell from 17% in 2023 to 11% in 2025.

Other high school age groups also saw a decline in the same period, after experiencing sharp increases in the share of LGB identification between 2019 and 2023. For those in 11th grade (16- and 17-year-olds), the number of LGB-identifying teens fell from around 18% in 2023 to 15% in 2025 , while for 12th graders (17- and 18-year-olds) the number fell from 18% to 16%.

That decline is driven “almost entirely by girls”, according to Twenge. Among high school girls, LGB identification fell from 27% in 2023 to 22% in 2025. In 2015, only around 13% of girls identified as LGB.

The most significant decline is among girls identifying as bisexual, with the number of ninth grade girls describing themselves as such falling by half, from 26% in 2021 to 13% in 2025.

For teenage boys, the numbers have remained more steady. In 2015, the percentage of high school boys identifying as LGB was only 5%, yet it rose to 9% in 2023. By 2025, that had fallen to 7%. While the number of high school boys reporting at least one same-sex partner has been steadily rising since 2015, the number for girls peaked at a 2021 high of 30%, and has since steeply declined to around 22%.

The figures come as the Trump administration announced this week the rescinding of Title IX, a Biden-era regulation that extended sex discrimination protections to also include sexual orientation and gender identification.

Eric Kaufmann, professor of politics at the University of Buckingham, told UnHerd that there were two theories behind the steep drop in LGB identification. First, a “hostile environment” created for non-heterosexual people in “Trump’s America” — a theory he argued lacked evidence.

The second, he argued, was the “fading of a trend” in LGB identification. Kaufmann said that identifying as LGB had been “fashionable” for a period, pointing to the much higher number of young women identifying as bisexual than reporting having had a same-sex partner. He argued that this gap suggested that LGB identification did not map on to actually having same-sex relationships.

“This pattern is exactly what we see on trans identification as well,” said Kaufmann. “It’s largely a contagion of fashion.”