On seasons four and five of “American Idol,” when the semifinals featured 24 singers, one-third of them were teenagers – eight each season. When this season’s semifinalists were named on Wednesday, only three of the 24 were in their teens: 17-year-old Sanjaya Malakar, 17-year-old Jordin Sparks and 19-year-old Stephanie Edwards. The numbers prompt the question: Is “Idol” growing up? Since raising the age limit to 28 for season four, singers approaching 30 have dominated the show, from Taylor Hicks, Chris Daughtry and Elliott Yamin to Bo Bice, Constantine Maroulis and Nadia Turner. And in season six, eight of the remaining… Read more »