The wold was destroyed when the sun flares hit. Some of the major cities were saved for the people who were still healthy. Eventually even the most protected cities fell to the cranks who either drove all the healthy people to the wilderness or ate them.
his parents house burned down because his fathers anger got the best of him - alcohol and all. sean was abused, beaten badly and cut with knifes when bad. his mother never did a thing: in fear the same would happen to her.