I agree, a lot of it is under socialization, and I've seen a lot of owners pet their dog when it was scared, only reinforcing the behavior. And have you watched America's Funniest Home Videos? There are a ton of videos of people purposefully encouraging aggression, resource guarding, scaring the dogs, and flat out being bad owners, all for a laugh.
I have a Toy Poodle and a Miniature Dachshund, my Toy Poodle was purchased by my grandma years ago when I was little, she raised him with a lot of hitting and punishment. Now that I'm older I have sort of taken over his training and he is a awesome little bugger. Loves people, confident, knows tons of tricks including "sneeze". I'd do sports with him if he didn't have poor structure. And when he can turn the energy knobs up to 100% in a split second.
If we have a new guest, or an old friend comes over he'll start racing around them, jump onto the couch, growl, play bow, bark, and take off. Over and over.(Tazzy, named after Taz the Tasmanian Devil for his zoomies.)
He hates other dogs though.
Before my grandma got my Dachshund he had lived the first 9-12 months of his life in a kennel. He is a tenacious little thing, but is very untrusting of strangers. He had a seizure awhile ago, and ever since he hasn't been the same, he doesn't retain training that well anymore. The vet said it was from the seizure and to keep a close eye on him, he hasn't shown any pain or had one since. He's just odd now.
I'd be worried if a small dog owned by an idiot owner grew large.
