In America, college students normally graduate at about the age of 21. Cho Seung-hui, when he went on his murder spree was reportedly in his senior year, but aged 23. Somewhere along the line, he lost a year, or maybe two. Possibly when his family moved to the U.S., since he seems to have graduated late from high school. Perhaps it is of no great significance, but I have not seen that gap explained. What happened?