An individual was adopted at birth and raised in a stable, supportive, and nurturing home environment. Their biological father, whom they never met, has a documented history of impulsive behavior, disregard for the rights of others, and repeated legal issues. In early adulthood, the adopted individual begins to display significant impulsive antisociality and a notable lack of empathy, despite having no history of abuse or neglect. Based on this scenario, what is the most likely primary contributing factor to the individual's behavior? Explain your reasoning.