Dr. Joel Nigg talks about ADHD in his March 14, 2012 lecture at UC Davis MIND Institute. He explains poor parenting and poor teaching indeed can make the ADHD issues worse, but that often times the 'poor' parenting and/or teaching is actually driven by the ADHD behavior, with out the behavior, these parents and teachers look much more positive. He says, though parenting and teaching indeed can have a positive impact on ADHD,  these are NOT the cause of the ADHD.  He goes on to say, " We are looking at dietary factors, toxic factors, biological insults that I am becoming convinced play a role in ADHD by altering neuro - development in subtle ways in vulnerable children."  He uses the example of lead, that we've very much lowered our exposure to lead in the US through regulation, but we still find lead in every individuals blood. Children with ADHD indeed do seem to have more lead and even very low levels of lead have a cognitive effect that looks like hyperactivity. Could their genetic make up have a role in having a higher level of lead in their blood? This is just one environment toxin that they are looking deeper into being an important factor for the cause of ADHD in the vulnerable child.  Watch his whole presentation here. http://www.ucdmc.ucdavis.edu/mindinstitute/videos/video_dls.html#dls12