Percent by age having sex for the first time in the United States, for those born from 1984 to 1993. For females up to 11 the majority of first sex is non-consensual. For 4.8% of females who are 17 to 20 years old when they first have sex, it is non-consensual. 17 year old males and females are more likely to have sex for the first time at that age than any other age.