American boy band Mindless Behavior were formed sometime in 2008 so they have been around, give or take three years. Before they released 'My Girl' they trained for two years and all four members are said to be in their early teens. You can read more here: http://www.ask.com/wiki/Mindless_Behavior
All the boys in Mindless Behavior are 14 years old. They have gone from touring in small high schools to opening for sold out tours of The Backstreet Boys and Justin Bieber. For a full bio on the boys, check out their website at http://www.mindlessbehavior.com/bio/default.aspx.