As a Master of Science Genetics --> Genetics are key!
If you have bad genetics you can never be a PRO-bodybuilder...
(Not saying you can't be huge! --> Just not "Freaky" enough to make it to the World-PROS!)
Fenotype = Genotype + Enviroment
The more we process info from HUGO the more we realize Enviroment plays a much less significant role then we thought!
That's why we prefer not to prescribe medicine when there's no need for it
--> Nothing can ever come even close to the bodies own Homeostasis (perfect balance), if adding something you always "disturb" something else!
Even after 3000 years of medicine we still don't know 0,001% about how the body works! --> That's why there are so much disease we can't cure yet and so many mutations of them (co-evolution of pathogens as described by Darwin)...
If you are small in size doesn't necessarily means you have bad genetics (e.g. everyone has a certain ratio of slow to fast musclefibers which can not be altered) but if it can be proven that you have bad genetics for musclebuilding (because maybe they are good genetics for something else

) then take all the medicines/supplements/gear you want and train and diet as much as your body can stand but you will never reach a point other then that the body permits you
(steroids for instance shift that limit by a small factor but what most people think that you couldn't reach that point naturally without gear is nonsense, you can always reach that maximum although maybe requiring 24/7 training and dedication but still --> steroids just make you come to that MAX much faster, but still there's only so much {muscle}mass a body can hold without resorting to unconventional help like growth factors!)
I'm really going to laugh if anybody doesn't agree with me since that would be real hypocritical
(my study teaches me that nothing can make up for genetics)
for it would probably be the same guys who always scream loudest that dieting without proper diet and cardio (so just diet-aids/gear) or juicing without proper training and diet doesn't work
(P.S. One more time being skinny doesn't mean you have bead genetics for muscle building --> To establish that knowledge you should take numerous tests, although in most cases it probably would be so seeing the old theories of endomorphs, mesomorphs and octomorphs --> Meaning gaining wouldn't be impossible but just harder then people with better genetic make-up, compare it with fat people eating and trying to lose weight opposed to skinny people)