Carlisle: I was attacked and turned during a raid on a vampire coven
Esme: Carlisle turned me after a suicide attempt spurred by the loss of my child
Edward: I nearly died from the Spanish influenza after watching my parents die from the same pandemic.
Rosalie: I was raped and beaten by my drunken fiancé and his friends and left to die
Alice: I was hunted by a tracker after being institutionalized by my own family and turned for my own safety
Jasper: I was turned to be used to create an army and was forced to slaughter newborns
Emmett: bear.