I don't see how a number is relevant to how I decide it is appropriate to share something with my son. That should be up to a parent to feel into for themselves I believe.
Discussion
It's relevant because the legal system uses that number.
In general I defer to parents to make the best decisions for their children.
Obviously at age 18 in the United States they legally are recognized as an adult who now can make their own decisions, with exceptions made for the drinking age which the states were strong armed into by withholding federal highway funds.
I hear you. Its not relevant to me is all I am saying.