Everyone has already added all the main factors. I'd like to add not listening. We never really listen to our children, just because they are young does not mean they don't deserve a voice. I talk to my children constantly, they aren't born ‘naughty’ they act in ways society views as incorrect but most of the time it's frustration due to not being understood or listened too. They a little humans, they feel, think, want, dislike just as adults. But they are not quite literate enough yet to say ‘ im having a paddy on the kitchen floor mum because I wanted the same drink as my siblings but you didn't listen instead you told me to stop moaning’