It depends on who bred the dog or if it was even purebred. Show breeders breed the bigger, wider, prettier dogs with more feathering, while working/hunting breeders breed for working ability and worry less about looks, but I'm not sure what size range is average for a working Golden, but I'm pretty sure they aren't as stocky. Backyard breeders breed anything of any size, shape, temperament, health so it could very well be from one of them.

Don't know if this was much help, but there are more Golden knowledgable folks that will be able to give more info.