Some states do not permit sex between a student and a teacher, even if that student is 18 and legally an adult. It’s all about power and the fact that someone in authority (a teacher or an administrator) can have an adverse influence over a student — “You either have sex with me or I’ll fail you.”
Does that carry over into criminalizing relationships between college professors and students? If not, why not? What is the difference between an 18 yo high school senior and an 18 yo college freshman?
Even though I'm a father with daughters, my attitude is that there needs to be an age where you consider a young person to be a complete, self-responsible adult, and 18 sounds like a good age.