Arginine and HMB together provide great results. Two independant studies done, one on athletes and the other on HIV patients, the results in both studies were that the people taking the Arginine / HMB combo were gaining quite a bit of lean tissue (including HIV patients) than the same study members not taking the combination.
HMB is by itself has not been very good, but stacked with Arginine it has been very successful for many people.
-------------- As far as genetics go, the skies the limit. You are limited only by your mental perception of it.