There's minor, and there's minor. Age of consent differs by state and country, quite a lot, everything from 14 y.o. to 21 y.o. plus special case exceptions by court.
Remember that before making absolute statements about mental powers.
By the way, coerced sex (sometimes rape, sometimes assault, sometimes pimping, in some places prostitution) is illegal among adults too. You can keep it extra illegal for minors.
Minority should not be an absolute but treated as a high bar. (The younger, the higher.)
Unfortunately legislatives are black and white in most countries, and people accede to it.
