I'm currently in an 18+ FC and the ones I used to run myself were 18+ not because we were an ERP guild; but rather because sometime subject matter can get dark and mature; as in non-sexual. Like Aurou, said it's- I believe mostly to protect the guild and not have the concern that there might end up being an angry Mama-tiger out there somewhere.
This being said, I'm certain there are some FCs that are not age restricted, and it's best to let your FC/LS leader know.
Edit:
You may wish to join more 'general' LS.
Infact the Leveler's LS might be a good start: http://ffxiv-roleplayers.com/showthread.php?tid=15893
Maybe; Heavy RP http://ffxiv-roleplayers.com/showthread.php?tid=8608
And perhaps Hugs & Cake http://ffxiv-roleplayers.com/showthread.php?tid=10815
Rp Events & Notices: http://ffxiv-roleplayers.com/showthread.php?tid=14942
but you'll have to check with their leaders.
This being said, I'm certain there are some FCs that are not age restricted, and it's best to let your FC/LS leader know.
Edit:
You may wish to join more 'general' LS.
Infact the Leveler's LS might be a good start: http://ffxiv-roleplayers.com/showthread.php?tid=15893
Maybe; Heavy RP http://ffxiv-roleplayers.com/showthread.php?tid=8608
And perhaps Hugs & Cake http://ffxiv-roleplayers.com/showthread.php?tid=10815
Rp Events & Notices: http://ffxiv-roleplayers.com/showthread.php?tid=14942
but you'll have to check with their leaders.
Nohni Vhaze || Khad Dotharl