Transgender adults who undergo gender-affirming surgery may first begin questioning their biological sex as early as age 7, a new study has found. In research published Monday by JAMA Network Open, the authors found that, among 210 transgender men and women, most first experienced gender dysphoria — feeling their emotional and psychological identity to be opposite of their biological sex — after their sixth birthday. The study may be the first to provide insight into the age of initial experience of gender dysphoria among trans Americans, researchers said. “For parents, these findings should provide some reassurance that what they’re seeing in their children is natural, that it’s not a ‘phase,’ as some have described it,” study co-author Maurice Garcia, a urologist at Cedars-Sinai Medical Center in Los Angeles, told UPI.