why some dogs are aggresive while others not

why some dogs are aggresive while others not?
who is to blame? can you blame the owner for raising the dog in that fashion?
or the blames reflects on the breeder.

Genetics / breeding
Social development in key life-stages
Environmental factors
Behavioural conditioning / reinforcement
Perspective problems / misjudging situations
Misdirection of drives

check out this video, it's the Russian Silver Fox Experiment...

https://www.youtube.com/watch?v=YbcwDXhugjw&feature=results_main&playnext=1&list=PLCA9F88C63018BF86

I dont know, I raised all my dogs the same. But Kaito is a mFer...the other day I was letting one of my neighbors kids give him some chicken. I told him to sit everytime he handed him some. So I guess he gets irritated by me and tried to bite back at me when I press his but told him to sit. Ive just about had it with this dog.....In a couple weeks Im putting him down...I cant deal with that type behavior.

That video is a great way to prove that temperament is genetic! I highly suggest those who haven't watched it to sit down and take a few minutes out of your day to do so...great info!