Is it OK to have sex with kids?

[DrDolittle]

A child is emotionally and psychologically too immature for a sexual relationship,

What evidence do you have suggesting a child is not mentally capable of enjoying sex and understanding its significance?

especially with an adult.

Would it be different with another child?

The part of the brain that is responsible for reasoning and decision making is not fully developed until the early twenties.

Then why do many nations permit teenagers to have sex, drink alcohol, drive cars etc?

It does hurt them, obviously more than you understand.

Please explain in what way it hurts them.