Haha, ok.
Myostatin is a protein that limits how much muscle your body will have. Research is still ongoing to try and block this protein for use in muscle wasting diseases & of course once someone finds something that works it'll no doubt be taken by bodybuilders.
The Belgian Blue cow in the picture has a gene mutation that stops it from producing myostatin which is why they're so huge. Some humans also have a similar mutation but it's really rare. Nothing bad seems to happen to the people without this gene, it seems like it's really there as a left over gene to limit how much food a human would need since more muscle needs a lot more energy.
OK, back to the guessing game :439: