No human society in the history of human society has claimed this, because it's ridiculously stupid. If you want to claim this, okay. Great, parents can't consent for their children. Since the document you don't consent to is the only thing that makes it illegal for me to murder you, ..., it's now okay to go out and murder every child, because they haven't explicitly consented.

Instead, of course, we discover that parents in fact, sanely consent for children until those children are capable of consenting or not consenting for themselves.

We also discover the concept of implied consent, whereby people using the benefits of a contract have also consented to the burdens.

No. It's not okay, because the children did not consent to be murdered.

Can a parent consent for the child to have sex? Of course not. A parent can't sign their child's life into debt.

Parents can not consent for their children, especially when that consent entails being conscripted into military service, taxed, and being put in prison for possessing a plant.

You should re-read Hobbes. Outside the social contract we live in the natural state of man, where our rights are to do whatever we think necessary to ensure our well-being, no matter the consequences to anyone else. Without a state, from where do you derive the right not to be murdered? The strength of your own limbs, and little else.

> A parent can't sign their child's life into debt.

Student loans aren't actually very far away from that. (Not everyone taking out a student loan is over 18 or the local age of majority, which I realize that you haven't personally consented to what that age of majority should be.)

What are you talking about? I consent to things for my children all the time. My son had elective surgery at ~18 months imposed on him without his consent, that would have been potentially criminal to do to an adult.

I genuinely don't understand what you mean by this point.