More than half of the whales in SeaWorld’s collection share Tilikum’s aggressive genes.  This argument conflicts with the film’s overarching claim about captivity triggering aggression in whales. But “Blackfish” also suggests aggressiveness can be passed on to a whale’s offspring.  The movie claims SeaWorld has made Tilikum its top breeder. That’s a bad thing, the documentary argues. The movie suggests that a reputable breeding program wouldn’t rely on an animal with a history of aggressive behavior but doesn’t offer any scientific backup that aggression can be inherited.  Mark Simmons, a former SeaWorld senior trainer who’s since spoken out against the documentary, told the “Blackfish” crew that Tilikum was an outlier.  Animal trainers often discourage owners from breeding aggressive animals but behavioral scientists who study humans and animals often emphasize the influence of both genetic and environmental factors.  While some studies have focused on a gene linked to aggressive behavior in humans, for example, most research has at least acknowledged the role of outside triggers.  Indeed, University of Notre Dame anthropologist Agustín Fuentes sharply panned the notion that biology is the sole determinant of hostile behavior in humans in a 2012 Salon article. His piece also cited research involving animals but not specifically killer whales.  SeaWorld says Tilikum fathered 10 of the 29 killer whales at its three parks. That means about 34 percent of SeaWorld’s current killer whales share his genes. The park says none of these orcas has aggressive tendencies.