Amy It focuses more on the romance than other YA books and describes some frightening genetically altered kids so I wouldn't recommend it for the 12 year old. If you are looking for Hunger Games or Divergent type books, I would recommend these series - Monument 14, Altered, The Program, Article 5, Taken, Skylark and The Testing.
Eleanor Jones Its great for mature 13 year old and above, I read it as a 14 year old and I liked it however I also defiantly wouldn't recommend it for a 12 year old or anyone just starting middle school. Amy's right THE TESTING SERIES IS AMAZING for a 12 year old and everyone else to!!!