Poverty, mental health and school all may play a role but at the end of the day the responsibility rests on parents. Unfortunately in todays world it seems parents act like victims. If parents aren't doing their job at home, then what teachers teach kids in school goes to waste.
Psychology has taught us much about nature vs. Nurture.
When Harlow conducted an experiment using baby rhesus monkeys, they were separated from their mothers at birth. They were then put in cages and given the choice to either choose a mechanical thing that was covered in cloth or one that was made from wire with a bottle to feed them, They mostly chose the one with cloth as it provided warmth and care. And when the cloth was taken away, the babies became devastated and some even died. The ones who were in total isolation for more than 90 days became permanently damaged.
Another study was conducted with Bobo dolls. Adults were told to hit the Bobo dolls with children observing. If the adults did not have any harmful consequences, the children would then mimic the same actions with the Bobo dolls without being told anything and would even start using other things such as play guns or vulgar language in which the adults did not use.
Parenting styles such as neglect or chaotic parenting also have a huge impact on a child;s future. They could either become hostile or insignificant towards their peers or could become super clingy and be prone to get picked on.
Yes, poor parenting is the primary cause of violent and aggressive behavior in children, because parents have so much say over how a child develops. The same child can act completely differently depending on who is in charge of them. Children take their cues from who is around them, and if the parents are problems, the children will be too.
Instead of trying to work three jobs, how about live within your means and spend time with your children? Instead of drinking every night, why not sober up and become a "real" parent? Many men and women think they want to become parents but can't get past their hormones at the moment of conception. Instead, why not think about the consequences for the next 20 years and wait to have children until later? Medical science is advanced enough to where women in their early 40s have perfectly healthy babies. There is no reason to have kids and get married at any age before 21. Humans don't die at 40 anymore like in the Paleolithic Era. With lifespans approaching 80 and more people living past 90, we can wait to have children later in life.
I believe poor parenting or a lack of parenting can lead to violent or aggressive behavior children. I think more often than not, it is a lack of parenting that really leads to the problem. I believe the children in America are often left to their own doing and ignored by the their parents for the most part.
Poor parenting is responsible for a child who is being aggressive not receiving the proper punishment or training. However, that punishment or training is no guarantee that a child's tendencies will be curbed. We as parents can redirect but that does not always mean that the behavior will completely change.
No, poor parenting is not the primary cause of violent or aggressive behavior in children. I believe that violence in media is the main cause in violence among kids. There have been kids from great homes that end up shooting up schools, like the columbine kids. If a kid is crazy he's crazy.
Although parenting does play a role in the behavior of a child, their is also much more that contributes to the behavior of a child. There have been many study cases that show that a child may have great parents but chooses to make bad choices based on influence of their surroundings. Parent's can only show their child the ethically right things to do in life but it is ultimately up to the child to make the right decisions. So although there are cases of bad parenting affecting children there is also good parents who children may have gone bad.