In our system ...we don't really have anyone who is a minor. Sparrow acts like a kid, but isn't human and is probably an adult for her species.
Both Bell and Shang ...well, Bell we met when we were 11; he was 12 or 14; can't remember which. Not only has he grown with us along the course of time (as he's using my brain and my brain has largely matured), but when we were younger we realized that this-world rules, regulations, and laws don't really apply in the spirit world. So for instance, even though we were intimate when we were younger, it wasn't what it would be according to U.S. law, especially as I could feel his thoughts and knew that he wasn't trying to manipulate me.
In other times and places, the age of consent has varied greatly; for example, in Japan it's only 14, and that's in the modern day. In a lot of places, people get married very young, and I would not as a blanket statement say that all of these marriages were wrong. So we don't have a strict code of morality as regards what happens in inner-world, because our experience has taught us that "laws" and the philosophies behind them are culturally-specific; and that for the benefit of the body they need to be obeyed, but not necessarily agreed-with.
Shang basically seems to be fairly ancient, though s/he doesn't look like it. <!-- s

--><img src="{SMILIES_PATH}/icon_e_smile.gif" alt=":)" title="Smile" /><!-- s

--> Both of these spirits have links to Classical China, and I'm still not great at clearly demarcating where one ends and the other begins -- I should probably work on that. There is also Mist, whose age we can't tell; like Shang, she's also an external spirit. Blaze is the age of the body or slightly older. Rose, we never really thought to ask her what her age is. <!-- s

--><img src="{SMILIES_PATH}/icon_razz.gif" alt=":P" title="Razz" /><!-- s

--> I'd think early twenties. I wouldn't be surprised if the baby-clock is hers...(for some reason we are finding babies [especially little Asian babies] adorable now, which never happened before. I blame the birth control [it made it so that I don't have to fear an unwanted pregnancy].) <!-- s

--><img src="{SMILIES_PATH}/icon_razz.gif" alt=":P" title="Razz" /><!-- s

-->
Alcohol isn't really an issue for my system. We can't drink anyway because of our medications; plus, alcohol makes us angry and sad at the same time, so it's not really anything for us to seek out. I don't really think there are any other age-related issues besides driving? which is also not as much of an issue for me because I don't yet have a license. I've read and seen that this isn't unusual for my generation, though.
I think that's it? <!-- s:? --><img src="{SMILIES_PATH}/icon_e_confused.gif" alt=":?" title="Confused" /><!-- s:? -->
-- Host/Blaze<Io (Io is a subpersonality of Blaze)