Ah, the latest muscle wunderkind
The last kid like this is now in his mid teens, and, having escaped an abusive training regime of his father (after his parents finally split), looks nothing like as muscular as he did when in single digits.
His dad refuted claims that his boy was using steroids, or any kind of pro-hormones, saying his success was down to a 'secret' shake, the ingredients of which were natural, though he refused to allow his son to have blood tests to prove it.
When off these shakes, the lad quickly returned to a 'healthy' normal active looking lad, and his dad ended up in prison.
Now history is repeating itself with this kid. Simply put, the pre-pubescent male body is biologicaly incapable of producing enough testosterone to cause muscle hypertrophy.
This kid is being spiked with gear, at a time when his physiology is still developing.
He should be removed from his home environment immediately for his own safety, as surely as would happen if a child's parents were making them smoke crack.