"Most children are born into one of the five factions," Evelyn explained. "There is a ceremony the year they turn 16 to choose one for themselves. Most people stay in the faction they were born into. Tobias was born into Abnegation--the Selfless. Going from that to Dauntless is practically unheard of. It hasn't happened in almost two decades. His father is an Abnegation leader: Tobias's defection was seen as a sign of weakness, for all that the factions teach 'faction before blood'."