Explaination with spoilers - there were 3!
A few summaries seem to be confused. There were a total of 3 children. The first child, the original Tommy, who was actually Florences son, died by falling out a window, due to a dog jumping on him. The second child (I don't remember his name), was a kidnapped child who was pushed down a flight of stairs and killed when he remembered who he really was. Finally, there was Billy/Tommy, who was kidnapped at 2 or 3 years, and started to remember memories from his old home/playground around the age of 10.share