Children who display behavior unlike what’s expected for their sex are more likely to face abuse, according to new research from the Harvard School of Public Health. 

The study, published in the journal Pediatrics last week, says that gender nonconforming kids are more likely to suffer physical, psychological or sexual abuse from adults. “Discrimination against nonconformity” affects about 10 percent of kids and is likely to leave lasting effects, including post-traumatic stress disorder. 

Using the nationwide study Growing Up Today, researchers looked at responses from 9,000 young adults who recalled childhood experiences. These memories included feelings of masculinity or femininity, media characters they imitated and whether they suffered abuse.

Those who reported the most gender nonconformity were more likely to have been physically, psychologically or sexually abused, the study says. Young adults who didn’t conform to gender norms in childhood were twice as likely to suffer from post-traumatic stress disorder than those who did conform.

This is such important work, and it’s one of the biggest reasons we need to let our kids dress how they want, play with the toys they want and make the friends they want. Kids are kids no matter how they identify, and how we treat them at an early age makes a huge difference.