doubt serial killers are "born that way"---increasing evidence points to many serial killers and single murderers having pre-fontal lobe brain damage,also known as "soft" brain damage---the book Guilty By Reason Of Insanity sheds a lot of light on this--2 authors did brain scans on a big number of killers and found a large majority had this problem in their brain---cause is usually the result of childhood beatings and/or accidents,resulting in truama to the brain--Bobby Joe Long,Tampa's serial killer,had two serious motorcykle accidents resulting in head injuries both times--Danny Rollings was beaten hundreds of times---The "Monster of the Andes",the south american serial killer,who murdered dozens of children,was severly,beaten,raped,and tortured as a boy--but many serial killers have refused to be tested for brain damage,so this theory is incomplete--serial killers have been around for over a hundred years,and not just in the USA--Canada has had several,Britain,France,and Germany had serial killers many times over the years--1939,in France,the last public execution by guillotine,was a serial killer--Britain had child serial killers even during WW II---the wild,drug-taking comedian,Sam Kinison,was a very shy quiet boy until a car hit him,causing a severe head injury--after that,as his brother relates,he became a totallydifferent person,eventually becoming a frenzied teenage evangelist---some serial killers have other traits,such as cruelty to animals,illegitamacy,lower-middle class upbringing,born from prostitutes,or having a mother who was married three or more times--lots of self-hatred also,the attempted suicide rate of killers and serial killers is enormous--see The Mammoth Book Of True Crime for more info,Volumes 1 and 2