Just one thing to add
When your parents do decide having a dog that size jumping up isn't a good idea because it has always been rewarded before it could take quite a while to correct, possibly much longer than it would if it had never been rewarded from the start. Don't give up

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It sounds like you are doing a great job teaching your dog 'good manners' but i agree that your parents are somewhat letting the side down! As already been said try explaining to your parents that should a young child get jumped on and gets hurt, wether he is 'being friendly' or not, if the parents of that child report it your dog could be in serious trouble! The powers that be won't care that he just wanted a fuss, they will see an out of control dog that is a danger.
My 7 month old pup jumps sometimes, and being a 25kg GSD it's not a 'cute' behaviour that gets her a fuss, it's an unwanted behaviour that gets her removed from whoever she is happy to see!
You could leave a houseline trailing on him so whenever he tries to jump, even if its on your parents, you can stop him and tell him NO and only let him get to greet anyone when all 4 paws are firmly on the floor
Keep it up, and keep drilling into your parents that if they don't help you address his jumping, they may well be signing his death certificate!

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My dogs go on the lead or shut away when I get visitors. The visitors have come to see me, not the dogs, so there you go.
When out, train the dog to sit to greet strangers, and reward that. And work on recall.
It is easier to train an alternative action than to stop one.

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I'd take a guess and think it's more likely it's the parents' house

Good advice given through the replies. You can't afford the risk of a fully grown dog that size jumping up on people. You have to get your parents on board with the training, and they have to start now.