He should just juice a little and go Hollywood. He has the connections and the genetics to be an action star and his acting ability can't be any worse than his dad. He shouldn't even waste his time competing in bodybuilding.
Arnold started taking D-bol when he was 15, therefore this Mexican version will never have a physique like his dad.
I would attribute Arnold's development (size wise) to starting drugs at such a young age, more so than his genetics. I wonder how long he took it without a break. In his later years he only took it for 3 months before the Mr. O. Arnold cut his training back drastically and looked average when he was off the gas. The D-bol and Primobolan sure worked wonders for him. A few guys that trained at the original Gold's told me that he took Parabolan too, but Arnold never admitted to that publicly.
