the point about any such study is that it indicates trends rather absolute correlations, so the existance of a counter-example proves nothing. They are interesting things to discuss - sometimes they lead to discoveries that are significant, sometimes they prove to be false leads; they need to be held gently, and probably not acted on aggressively (TB was thought to be hereditary, so the way to get rid of it was sterilisation, whereas in fact it is curable with antibiotics.) |