But you gotta admit, the drugs worked wonders for Arnold. He looked superb! Give someone the same shit and dosage Arnold took and no one will look like him - enter his genetics! 

Lou looked pretty close to Arnold at the same age.........
Yes I've heard as young as 13 as well. I'm more likely to believe 15-16. Either way Arnold started using at a VERY young age. He had to in order to achieve the physique he did at 18. I mean to step on stage with pros like Chet Yorton at 18-19 years old? Come on. Hence why Arnold's "genetics" are overrated. You take any fairly strong, well developed teenager and put em on dbol and primo or whatever else he used and he grows into a bodybuilder and of course society will think he's a genetic freak.
Actually back then there was no "
professional" BBing. The top BBer of the time period was Bill Pearl, and he could not make a living purely from BBing-so he opened gyms.
Arnold was the FIRST true BBer to earn a living
purely from BBing and nothing else. He did guest posing, seminars, gym openings (he appeared at Clany Ross's gym opening in 1978) and had a fairly decent mail order business.