In between watching the Red Sox win for their 7th straight against the New York Yankees, I was flipping to an interesting show regarding a three-year-old named Liam Hoekstra - aka the World's Strongest Boy. Here's another good writeup about him.
Fascinating story. The kid can do an un-assisted pull up (palms out), three point pushup stance, etc. He has 40% more muscle in his legs than a standard three-year-old. Strength tests peg him at having the strength of a six or seven year old. The show on The Learning Channel demonstrated this as well as the kid scaling his parents refrigerator unassisted (he grabbed on to the vertical handle, pulled him self up until he could reach the top!)
At first the doctors suspected he did not have the gene that produces myostatin (muscle growth regulation), but found that he has myostatin-related muscle hypertrophy, where he has terrific skeletal muscular growth and retains very little body fat. In fact the doctors are more worried about his inability to store body fat since his body may attack the central nervous system.
I'm sure that nutrition/exercise/supplement firms are just smacking their lips that science will uncover the secret to this for consumption by the general population. Like when myostatin was discovered in the 1990's, immediately advertised myostatin inhibitors became available to the market - whether any of them work effectively or safely is another discussion.