The percent of U.S. adults who identify as something other than heterosexual has doubled over the last 10 years, from 3.5 percent in 2012 to 7.1 percent, according to a Gallup poll released Thursday. Gallup found that the increase is due to ”high LGBT self-identification, particularly as bisexual, among Generation Z adults,” who are 18 to 25. It asked more than 12,000 U.S. adults how they identify during telephone interviews last year. It found that younger U.S. adults are much more likely to identify as LGBTQ than older generations. More than 1 in 5, or 21 percent, of Generation Z adults identify as LGBTQ, Gallup found. That’s almost double the proportion of millennials, who are 26 to 41, at 10.5 percent, and nearly five times the proportion of Generation X, who are 42 to 57, at 4.2 percent. Less than 3 percent of baby boomers, who are 58 to 76, identify as LGBTQ, compared to just 0.8 percent of traditionalists, who are 77 or older.