This is all camera angle.
He's 5'8" and only 168#. When I was 18, I was 5'5" and 175#. When I was 28 I was 5'5" and 230#.
If this kid is juiced, he's not doing very much. He's simply not big enough.
He may have tinkered with some Pump and Pose a bit on his arms, but, he's not really that big.
There are some folks who have myostatin blockade, but, it's doubtful the person you are referencing has it. He does have good "lines", but, is mostly small. If we was juiced he'd be upwards of 250#. He's simply too small and lack the tell tails signs of juice. Never forget that nothing is more "natural" than testosterone. Likely, this kid does have high endegenous tesosterone levels but he certainly doesn't have characteristics of someone with super-physiological testosterone levels. As I said, he's just to small.
Myostatin blockade happens in several species.http://en.wikipedia.org/wiki/Belgian_Blue
I haven't been to the gym in almost 3 months, and I weighed 207 this morning, at 5'5", and I'm not fat. Some of us are just better at it than others, and school ourselves on proper method. You would do well to eat.
Some folks are ignorant and really don't have any idea what they're looking at. With someone so small, and looking as he does, it's not likely that he's taking much, if anything. While ignorant folks may think otherwise, those of us who know, know better. Sometimes, folks have great genes. I've seen it lots of times. Just as some folks can't play basketball some folks don't have good bods, while others do. Some of the best bods I've seen have been on guys who are just good old farm boys. Best not to be ignorant.