God made humans sexually mature, i.e. physiologically adult, capable of reproducing, when they become teenagers, more or less (can start earlier, but by the time they’re 13, they’re certainly all into puberty, and girls can certainly get pregnant at that age).
In centuries past, many people did marry quite early on; this is documented. There are other cultures where this is still the case; they do not have any conception of ‘adolescence’.
Our extended adolescence and delay of adult responsibilities is stupid. Our laws punishing sexual relations between someone over 18 and someone under 18 but bearing secondary sexual characteristics, able to reproduce, are irrational.
If parents want to protect their children, they need to bring them up right with proper values, and keep them at home until they consider them marriageable. Maybe for some, that isn’t till 18, or 26; for others, maybe at 14, they’re ready. No reason why 18 should be the age; that’s completely arbitrary, and it isn’t when people become physically capable of reproducing.
The laws should be changed. Teach your girls not to be sluts, if you don’t want them fornicating. Encourage them to marry while their fertility is at its peak, rather than delaying for the sake of education and career.
P.S. There should be no such thing as ‘jailbait’; if a teenage girl flirts with an older man, and seduces him, he shouldn’t be criminally liable for engaging in consensual activity with her. Again, if fathers want to protect their daughters, it should be up to them to bring them up right so they don’t fornicate; it shouldn’t be the state’s role to punish men who take advantage of willing, consenting slutty teenage girls.