How much of that is a nature thing (bad breeding) vs. a socialization and training one?
I've heard of some breeds being more prone to anxiety/aggression due to poor breeding stock but didn't really know how much merit there was to that.
Good question. Usually, I've seen more health issues due to poor breeding. But yes, some breeds are more prone to anxiety/aggression issues. I think Weimaraners have anxiety issues while Chows are known for biting.
But I've seen a lot of new dog owners with their labra/goldendoodles that don't how to properly train and socialize their dogs, so that's one problem.
There have been a few puppies, I'm talking about 4-5 months that have come to the dog park and when other dogs try to interact/play with the puppy, the puppy's first reaction has been to attack. I can only guess the puppy was purchased at a store and the puppy is from a puppy mill and taken from it's mother/litter too early to learn any canine social skills or possibly just poor breeding with a dog that has behavioral issues.
We see the puppy(now a dog) when I take mine for a walk and the dog the owners will quickly alter their route to avoid us while the whole time the dog is lunging and growling and stupid owners are yelling at the dog "bad dog'.
But my biggest complaint is the barking. I think I've more that are barkers than are not.