The reason we know this is bullshyt is because most of us got spankings. Most of our peers got spankings. Yet most of them were not fighting teachers. And we didnt have that many fights in school. Which based on your "science",it should have been a royal rumble.
These studies are nothing more than the European making correlations to fit a narrative. You can do that about many things.
This little girl has probably built up an ego. That she is a bad ass,feisty,dont take shyt type of girl. This teacher challenging her couldve been a threat to her ego.
This is where 90% of violence comes into play. Someone has their public image or self image threatened.
It is false to pretend that kids base their self image or public image on their parents. Some kids can base their identity entirely on what gains them validation from the outside world. It may be validation at home or validation from society and strangers. When you live in an environment that has a culture that celebrates violence, machismo,not being p*ssy its a recipe for disaster. You will have people whove gained validation from their aggression. Challenging people who may not want to be violent. But their self image/public image they have created deems they have to. People are willing to die and kill to protect their self idealization when its in jeapordy.
Your studies leave out the fact that violence can be neccessary from a parent. When your validation stops mattering,some times to no fault of your own. Time to bring out the valuable teaching tools,aka the hands. Your image must be protected at all cost when you are a parent. If my actions and words have failed to gain your respect,time to escalate
.
Acts of violence dont neccessarily mean you are violent.
Gen. X posters who grew up getting the shyt beat out of them, going outside to sell crack and set murder rate records with their friends, talking about the current generation needing to experience what they did because things are so much worse now. 
