And from contextual evidence I could tell you that most of the people I know from FF forums are in their mid-late twenties/early thirties and a large number of people I play Final Fantasy XIV with are in the latter half of their thirties. I wouldn't use such limited evidence to make a sweeping generalization on the internet though, especially when the
consumer research suggests the average age of video game consumers is someone in their 30s these days.
Irregardless, if the consumers are aged in their 20s or 30s or 40s... someone aged 15, for example, is not exactly a young adult. By all accounts in most countries someone of that age would be classed as a child still.