Earlier quoted context omitted.
I didn't understand that part as well. As far as I know, kids can't sign contracts. They are not "geschäftsfähig" (business capable) until they are 18. Unless the parents explicitly agree to some contract.
Kids under 7 cannot enter into contracts at all. Kids between 7 and 18 can enter into contracts, either if those contracts are entirely without duties to them (e.g. they can accept gifts) or if their contractual duties are somewhat negligible (e.g. they can buy sweets from their pocket money) or their guardians agreed to them being able to enter into such contracts. All other contracts are provisionally void (?!, "sc…
Huh, that's interesting. I'm not familiar with German law, but in the Netherlands this would legally be simply not a contract at all. A contract (in the Netherlands) explicitly requires (actually is defined as such) that both parties have contractual duties, and a contract is the formalisation of the exchange of these ("this for that").
It makes a lot of sense too. If one party has no duties, they can't be held to the contract, so what's the use of even having one.