Something tells me the boy was not exercising his freedom, that he was not free to shoot his sister. Not only did the law not allow it, but neither did his parents.
That's not really the point here is it?
The reason he was able to shoot his sister was because of the gun. Why was there a gun in the house? Why was he able to get a gun? Because of the 2A, the NRA, the attitude towards guns in the US.
The NRA? Lets say the kid got a hold of a single shot .22 to kill his sister. Are you saying that this to is a gun that should be banned?
Mark