Guido -> yes I think that is the case to a degree, but surely there is still a scientific basis for one drug being more addictive than another. Or with more potential to cause addiction than another. For example there are drugs in which you can get hooked after just using a few times, and others take several months or even years of regular use to become an addict. So wouldnt it make sense to state that, although each individual may have a tendancy towards one class of drug over another, there is still a scientific base for one drug being more addictive than another?
