The Murder Gene

As the soft-spoken, highly intelligent son of missionaries in Morganton, North Carolina, Luke Chang gave no indication of the killer he would become. But after hacking into a teacher's computer at his school, a stint in the Marines was his only option.
As a young recruit, Luke was taunted for being a virgin who didn't cuss, drink, or smoke pot. That all changed when Luke met Casey Byrams, a fun-loving musician and fellow Marine from Cullman, Alabama. Their friendship set off a series of events that would eventually lead Luke to Pendleton, Oregon, where he brutally murdered nineteen-year-old Amyjane Brandhagen in August 2012. When Luke attempted to kill another woman almost a year later, Pendleton Police knew they had a serial-killer wannabe on their hands.
Some forty years prior to Amyjane's murder, Luke's maternal grandfather, Gene Dale Lincoln, murdered a young Michigan woman and attempted to abduct a twelve-year-old girl. The similarities between the violent actions of grandfather and grandson compels the question: Is there such a thing as a murder gene?