Originally Posted by dr wadd

I do not agree with the conclusions that have been drawn from that experiment, all it does is illustrate that any causative effects are not genetic in nature. As it does not fully account for all nuture effects, as the article itself highlights, it cannot be considered to have demonstrated its argument clearly.

It does not cover the issues of cause and effect adequately either. It does not examine whether it is likely if these people would have gone on to harder drugs if they hadn`t been taking cannabis. It is difficult to draw accurate conclusions without reading the original paper, but all that precis does is highlight an "interesting" statistical correlation, but doesn`t actually provide clear evidence one way or the other for the overall argument.