[quote=Lugubrious]
Given that the legal age is 18, this somewhat perturbs me.
[/quote]

It varies between states. Federal law says 18, but that only applies to sexual acts that involve travel between states, countries, or on federal property. This includes communication. For the rest, it's the purview of the states themselves, with 32 having the age of consent at 16, 9 at 17, and 10 at 18. 

The more you know.