Wilson, read this book and then get back to us-- Federal Bureau of Narcotics mob files--
http://www.amazon.com/gp/product/0061363855the answer, as others have said, is precisely NONE. Even talking about it as a "rule" is silly; it was a self-serving myth, that's all.
Also, while it's true the "War on Drugs" horseshit made things al around, there have been drug scares-- and lots of "good" white kids/women/professionals-- on dope ever since there was dope to be had: opium especially in later 19th c. and after cocaine and heroin were regulated, then made illegal in the 1910s, those drugs as well...
The REAL story that I've not seen explained well are the major U.S. dope players of the 1910s-1920s, when huge coke and heroin $$$ become available for the first time. Arnold Rothstein of course is credited as major heroin trafficker, or financier (who knows), with "Lepke" and Luciano getting in no later than 1930...
While the markets expanded with population etc (not to mention blatant CIA encouragement at various points) there's no question 'families' and their antecedents were there from the near start.
