i think the real cause of growth stunt is poor nutrition.
you always hear things like "don't do weightlifting because "insert
myth here" and unfortunately people believe it 
firstly some people are eating less than they should during
puberty, then they take up weightlifting, they'll be needing more
calories than ever, and if they don't fix up their diet, all the
nutrients they consume go to muscle repair and building, and
nothing is left for growth in height