"The lifetime prevalence of child sexual abuse and sexual assault assessed in late adolescence" - https://pubmed.ncbi.nlm.nih.gov/24582321/, which was cited by RAINN(Rape, Abuse & Incest National Network) on their statistics page https://www.rainn.org/statistics/children-and-teens

I know this might be quite shocking but in my experience, sexual abuse to children is unfortunately common. Remember the olympic gymnastics doctor that (convictedly) sexually abused "at least" 265 women and minor girls, with the overall scandal being (allegedly) over 500 women primarily under 18? How about the thousands of child sex abuse cases in the Boy Scouts? These are just the high profile cases. Literally "creepy uncle" jokes have been common crass comedy for decades.